Added text selection and copy support to TextFieldWidget.

Use Shift and navigation key (cursor, home, end) to select a portion of
text, and replace/delete/cut as appropriate.
Also provides support for selection with mouse (click and drag)

mods/cnc/metrics.yaml

@@ -6,3 +6,4 @@ Metrics:
 	CheckboxPressedState: true
 	ColorPickerActorType: fact.colorpicker
 	ColorPickerRemapIndices: 176, 178, 180, 182, 184, 186, 189, 191, 177, 179, 181, 183, 185, 187, 188, 190
+	TextfieldColorHighlight: 800000

mods/common/metrics.yaml

@@ -36,6 +36,7 @@ Metrics:
 	TextfieldColor: FFFFFF
 	TextfieldColorDisabled: 808080
 	TextfieldColorInvalid: FFC0C0
+	TextfieldColorHighlight: 195BC4
 	TextfieldFont: Regular
 	WaitingGameColor: 00FF00
 	UPnPDisabledColor: FFFFFF

mods/d2k/metrics.yaml

@@ -6,3 +6,4 @@ Metrics:
 	FactionSuffix-corrino: harkonnen
 	FactionSuffix-smuggler: ordos
 	FactionSuffix-mercenary: ordos
+	TextfieldColorHighlight: 7f4d29

mods/ra/metrics.yaml

@@ -15,3 +15,4 @@ Metrics:
 	FactionSuffix-ukraine: soviet
 	IncompatibleProtectedGameColor: B22222
 	IncompatibleVersionColor: D3D3D3
+	TextfieldColorHighlight: 562020

mods/ts/metrics.yaml

@@ -2,3 +2,4 @@
 Metrics:
 	ColorPickerActorType: mmch.colorpicker
 	ColorPickerRemapIndices: 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31
+	TextfieldColorHighlight: 1a1a1a