CppEditor: InsertDefFromDecl: Hide when definition already exists

"Add Definition Inside/Outside Class" was wrongly shown when there was
already an definition outside the class.

Change-Id: I6409080c6a1a3abdd4511f7db14ecb4f63458411
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>
CustomExecutableRC: s/Command/Executable/

A custom executable RC should have an executable to set up, not
a command. That is more consistent with the other RCs, too.

Change-Id: I7d71f9f93cd8294132a65fadf2e7a8885143c19d
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@digia.com>