CppEditor: Fix handling of "m_" in GenerateGetterSetter

If a variable's name is only "m_" it should not be recognized as a
prefix (resulting in an invalid/empty getter and meaningless setter) but
rather as a name with the "_" postfix. This way, it results in getM()
and setM().

Change-Id: I9a8249fc12319034b95532415f40b6c3183f7754
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
CppEditor: Allow single "m" prefix for GenerateGetterSetter

Task-number: QTCREATORBUG-12244
Change-Id: Iab666f003df04da97ed7f4aa47f9b979e319e9a4
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
Beautifier: Harmonize setting's translatable strings

Change-Id: I9b0a4b305415e1f97353bd4ebc2631634cebd1cb
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>