Core: proper gradients for ActionButton text part.

Conflicts:

	src/share/qml/common/ActionButton.qml
Core: opacity is not transparency.
Overall: get rid of transparentStyle, got it right.

Conflicts:

	src/plugins/krigstask/share/qml/krigstask/TaskbarQuark.qml
	src/plugins/sb2/share/qml/sb2/LauncherComponent.qml
	src/plugins/sb2/share/qml/sb2/SideView.qml
Core: avoid naming conflict in ActionButton.

Conflicts:

	src/share/qml/common/ActionButton.qml
Core: handle META key in KeySequences, thanks @amd63.
Core: default codec for C strs is UTF-8, fixes #1100.