Merge mer-3.1 into next

- Compiles w/o error; launch&quit possible.
- dist/gdb/ resolved by resetting to next, i.e., kept our version which also matches Mer version
- src/tools/sdktool/ resolved by resetting to mer-3.1, i.e., temporarily throwing out our changes - will be rewritten later.
- some changes to non-Mer parts of Qt Creator temporarily reverted.

FOR REVIEW SEE THOSE FEW COMMITS AT THE VERY END

MERGE #4 FIRST.

PLEASE DO NOT MERGE USING GITHUB INTERFACE - it always does a true merge AFAIK and this is not desired here.