Add basic .xrdb/.Xresources import plugin

Adds basic support for importing .Xresources and .xrdb files as Theme
resources.

Examples of terminal color schemes in .xrdb format can be found here:
https://github.com/mbadolato/iTerm2-Color-Schemes/tree/master/xrdb

Examples of terminal themes in .Xresources format can be found here:
https://github.com/mbadolato/iTerm2-Color-Schemes/tree/master/Xresources

https://terminal.sexy also supports exporting themes is Xresources
format.

test/import_plugins/xrdb/Test1.xrdb

@@ -0,0 +1,20 @@
+#define Background_Color #100000
+#define Foreground_Color #200000
+#define Cursor_Color #300000
+#define Cursor_Text_Color #400000
+#define Ansi_0_Color #000000
+#define Ansi_8_Color #000008
+#define Ansi_1_Color #000001
+#define Ansi_9_Color #000009
+#define Ansi_2_Color #000002
+#define Ansi_10_Color #000010
+#define Ansi_3_Color #000003
+#define Ansi_11_Color #000011
+#define Ansi_4_Color #000004
+#define Ansi_12_Color #000012
+#define Ansi_5_Color #000005
+#define Ansi_13_Color #000013
+#define Ansi_6_Color #000006
+#define Ansi_14_Color #000014
+#define Ansi_7_Color #000007
+#define Ansi_15_Color #000015

test/import_plugins/xrdb/Test1.xrdb.import

@@ -0,0 +1,13 @@
+[remap]
+
+importer="godot_xterm_xrdb_importer"
+type="Theme"
+path="res://.import/Test1.xrdb-754efb4c644076f3ce42897c010bc001.res"
+
+[deps]
+
+source_file="res://test/import_plugins/xrdb/Test1.xrdb"
+dest_files=[ "res://.import/Test1.xrdb-754efb4c644076f3ce42897c010bc001.res" ]
+
+[params]
+

test/import_plugins/xrdb/Test2.Xresources

@@ -0,0 +1,36 @@
+! special
+*.foreground:   #c5c8c6
+*.background:   #1d1f21
+*.cursorColor:  #c5c8c6
+
+! black
+*.color0:       #282a2e
+*.color8:       #373b41
+
+! red
+*.color1:       #a54242
+*.color9:       #cc6666
+
+! green
+*.color2:       #8c9440
+*.color10:      #b5bd68
+
+! yellow
+*.color3:       #de935f
+*.color11:      #f0c674
+
+! blue
+*.color4:       #5f819d
+*.color12:      #81a2be
+
+! magenta
+*.color5:       #85678f
+*.color13:      #b294bb
+
+! cyan
+*.color6:       #5e8d87
+*.color14:      #8abeb7
+
+! white
+*.color7:       #707880
+*.color15:      #c5c8c6

test/import_plugins/xrdb/Test2.Xresources.import

@@ -0,0 +1,13 @@
+[remap]
+
+importer="godot_xterm_xrdb_importer"
+type="Theme"
+path="res://.import/Test2.Xresources-2344fb3eca84b06f68214bc0cdb6b0ab.res"
+
+[deps]
+
+source_file="res://test/import_plugins/xrdb/Test2.Xresources"
+dest_files=[ "res://.import/Test2.Xresources-2344fb3eca84b06f68214bc0cdb6b0ab.res" ]
+
+[params]
+

test/import_plugins/xrdb/Test3.xresources

@@ -0,0 +1,36 @@
+! special
+*.foreground:   #eddfe4
+*.background:   #000000
+*.cursorColor:  #eddfe4
+
+! black
+*.color0:       #000000
+*.color8:       #6da3b8
+
+! red
+*.color1:       #1b0c13
+*.color9:       #ca956c
+
+! green
+*.color2:       #351b27
+*.color10:      #7ca7b9
+
+! yellow
+*.color3:       #563042
+*.color11:      #a2c9bc
+
+! blue
+*.color4:       #814b64
+*.color12:      #9aad72
+
+! magenta
+*.color5:       #b56b8d
+*.color13:      #82d0b7
+
+! cyan
+*.color6:       #d0a2b6
+*.color14:      #ae96d0
+
+! white
+*.color7:       #eddfe4
+*.color15:      #e6bfcf

test/import_plugins/xrdb/Test3.xresources.import

@@ -0,0 +1,13 @@
+[remap]
+
+importer="godot_xterm_xrdb_importer"
+type="Theme"
+path="res://.import/Test3.xresources-bec998d839dd0fca9b82fa130c7bada8.res"
+
+[deps]
+
+source_file="res://test/import_plugins/xrdb/Test3.xresources"
+dest_files=[ "res://.import/Test3.xresources-bec998d839dd0fca9b82fa130c7bada8.res" ]
+
+[params]
+

test/import_plugins/xrdb/xrdb_import_plugin.test.gd

@@ -0,0 +1,95 @@
+extends "res://addons/gut/test.gd"
+# Many themes in a similar format to Test1.xrdb can be found here:
+# https://github.com/mbadolato/iTerm2-Color-Schemes/tree/master/xrdb
+# Test2.Xresources and Test3.xresources randomly generated at https://terminal.sexy
+# and downloaded in Xresources format.
+
+
+func test_xrdb():
+	var theme = preload("./Test1.xrdb")
+	assert_true(theme is Theme)
+
+	var map := {
+		"Black": "#000000",
+		"Red": "#000001",
+		"Green": "#000002",
+		"Yellow": "#000003",
+		"Blue": "#000004",
+		"Magenta": "#000005",
+		"Cyan": "#000006",
+		"Light Grey": "#000007",
+		"Dark Grey": "#000008",
+		"Light Red": "#000009",
+		"Light Green": "#000010",
+		"Light Yellow": "#000011",
+		"Light Blue": "#000012",
+		"Light Magenta": "#000013",
+		"Light Cyan": "#000014",
+		"White": "#000015",
+		"Background": "#100000",
+		"Foreground": "#200000",
+		"Cursor": "#300000",
+	}
+
+	for key in map.keys():
+		assert_eq(theme.get_color(key, "Terminal"), Color(map[key]), key)
+
+
+func test_Xresources():
+	var theme = preload("./Test2.Xresources")
+	assert_true(theme is Theme)
+
+	var map := {
+		"Black": "#282A2E",
+		"Red": "#A54242",
+		"Green": "#8C9440",
+		"Yellow": "#DE935F",
+		"Blue": "#5F819D",
+		"Magenta": "#85678F",
+		"Cyan": "#5E8D87",
+		"Light Grey": "#707880",
+		"Dark Grey": "#373B41",
+		"Light Red": "#CC6666",
+		"Light Green": "#B5BD68",
+		"Light Yellow": "#F0C674",
+		"Light Blue": "#81A2BE",
+		"Light Magenta": "#B294BB",
+		"Light Cyan": "#8ABEB7",
+		"White": "#C5C8C6",
+		"Background": "#1D1F21",
+		"Foreground": "#C5C8C6",
+		"Cursor": "#C5C8C6",
+	}
+
+	for key in map.keys():
+		assert_eq(theme.get_color(key, "Terminal"), Color(map[key]), key)
+
+
+func test_xresources():
+	var theme = preload("./Test3.xresources")
+	assert_true(theme is Theme)
+
+	var map := {
+		"Black": "#000000",
+		"Red": "#1B0C13",
+		"Green": "#351B27",
+		"Yellow": "#563042",
+		"Blue": "#814B64",
+		"Magenta": "#B56B8D",
+		"Cyan": "#D0A2B6",
+		"Light Grey": "#EDDFE4",
+		"Dark Grey": "#6DA3B8",
+		"Light Red": "#CA956C",
+		"Light Green": "#7CA7B9",
+		"Light Yellow": "#A2C9BC",
+		"Light Blue": "#9AAD72",
+		"Light Magenta": "#82D0B7",
+		"Light Cyan": "#AE96D0",
+		"White": "#E6BFCF",
+		"Background": "#000000",
+		"Foreground": "#EDDFE4",
+		"Cursor": "#EDDFE4",
+	}
+
+	for key in map.keys():
+		assert_eq(theme.get_color(key, "Terminal"), Color(map[key]), key)