Patch bitness tweaks

[b100dian]

This PR against patch-bitness branch

• reduces the MANGLE_CANDIDATES to only one list (32 bit) for cpp code too
• adds a dbus call for showing getMangleCandidates() in QML Settings
• adds patchmanager2 bitnessMangle setting which e.g controls pm_apply and cpp refresh list mangling
• favours the editied patch for unapply if present

Switching the bitnessMangle after applying a (failed) patch may not work without unapplying all patches.
Maybe we should mark this as experimental, but the reason is somewhere in the same cache preparation.

[nephros]

Very nice!