Add transparency support for theme colors

Closes #19.

CHANGELOG.md

@@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 
 ## [Unreleased]
+### Added
+- Theme colors now support transparency.
+
 ### Changed
 - Set a default theme if no theme property has been set.
 

addons/godot_xterm/native/src/terminal.cpp

@@ -385,7 +385,7 @@ void Terminal::update_theme()
 		color_palette[color][1] = c.get_g8();
 		color_palette[color][2] = c.get_b8();
 
-		palette.erase(color) = c;
+		palette[color] = c;
 	};
 
 	set_pallete_color(TSM_COLOR_BLACK,         "Black",         0, 0, 0);