Add more features, bug fixes and bugs ;-)

Most notably:
- Reflow is now working. Terminal size will fill the window and
cols/rows will be resized/calculated based on window and font size.
- Added support for different fonts (i.e. bold, italic, bolditalic).
- Enabled blinking characters.
- Adde more tests and caught a few subtle bugs.
- Removed renderer code (which was part of xterm.js) and just
doing naive rendering in terminal.gd, but it seems to perform
a lot faster.

Still not working completely:
- vim (some weirdness going on).
- vttest (more weirdness).

Todo:
- Fix the above.
- Draw the cursor!
- Improve performance. Performance is still not great. The terminal
becomes unusable when running `yes` or `cmatrix -r`.

addons/godot_xterm/parser/escape_sequence_parser.gd

@@ -145,8 +145,9 @@ func set_execute_handler_fallback(target: Object, method: String):
 	_execute_handler_fb = { 'target': target, 'method': method }
 
 
-func set_esc_handler(id, target, method):
-	_esc_handlers[identifier(id, [0x30, 0x7e])] = [{'target': target, 'method': method}]
+func set_esc_handler(id, target, method, arg = null):
+	_esc_handlers[identifier(id, [0x30, 0x7e])] = [{'target': target,
+			'method': method, 'arg': arg}]
 
 
 func set_esc_handler_fallback(target: Object, method: String):
@@ -229,6 +230,7 @@ func parse(data: Array, length: int):
 			ParserAction.EXECUTE:
 				var handler = _execute_handlers.get(code)
 				if handler:
+					print("EXEC: ", handler['method'])
 					handler['target'].call(handler['method'])
 				elif _execute_handler_fb:
 					_execute_handler_fb['target'].call(_execute_handler_fb['method'], code)
@@ -243,6 +245,7 @@ func parse(data: Array, length: int):
 				var handlers = _csi_handlers.get((collect << 8 | code), [])
 				handlers.invert()
 				for handler in handlers:
+					print("CSI: ", handler['method'])
 					# undefined or true means success and to stop bubbling
 					if handler['target'].call(handler['method'], params):
 						continue
@@ -277,8 +280,13 @@ func parse(data: Array, length: int):
 				handlers.invert()
 				for handler in handlers:
 					# undefined or true means success and to stop bubbling
-					if handler['target'].call(handler['method']) != false:
-						continue
+					print("ESC: ", handler['method'])
+					if handler['arg']:
+						if handler['target'].call(handler['method'], handler['arg']) != false:
+							continue
+					else:
+						if handler['target'].call(handler['method']) != false:
+							continue
 				handlers.invert()
 				if handlers.empty():
 					_esc_handler_fb['target'].call(_esc_handler_fb['method'], collect << 8 | code)

addons/godot_xterm/parser/params.gd

@@ -75,6 +75,12 @@ func add_param(value: int):
 	params[length] = MAX_VALUE if value > MAX_VALUE else value
 	length += 1
 
+
+# Add a sub parameter value.
+# The sub parameter is automatically associated with the last parameter value.
+# Thus it is not possible to add a subparameter without any parameter added yet.
+# `Params` only stores up to `subParamsLength` sub parameters, any later
+# sub parameter will be ignored.
 func add_sub_param(value: int):
 	digit_is_sub = true
 	if !length:
@@ -88,6 +94,21 @@ func add_sub_param(value: int):
 	sub_params_length += 1
 	sub_params_idx[length - 1] += 1
 
+
+# Whether parameter at index `idx` has sub parameters.
+func has_sub_params(idx: int) -> bool:
+	return (sub_params_idx[idx] & 0xFF) - (sub_params_idx[idx] >> 8) > 0
+
+
+func get_sub_params(idx: int):
+	var start = sub_params_idx[idx] >> 8
+	var end = sub_params_idx[idx] & 0xFF
+	if end - start > 0:
+		return sub_params.slice(start, end - 1)
+	else:
+		return null
+
+
 func add_digit(value: int):
 	var _length = sub_params_length if digit_is_sub else length
 	if _reject_digits or (not _length) or (digit_is_sub and _reject_sub_digits):
@@ -97,10 +118,6 @@ func add_digit(value: int):
 	store[_length - 1] = min(cur * 10 + value, MAX_VALUE) if ~cur else value
 
 
-func size():
-	return params.size()
-
-
 func to_array():
 	var res = []
 	for i in range(length):