build system: use -std=c++11 instead of -std=c++0x if the compiler supports it
build system: add C++11 flag to wxWidgets test
mmg input tab: temporarily remove all occurrences of wxGROW
mmg input tab: create controls first, layout afterwards
mmg input tab: make all inputs and sizers grow properly

Fixes the issue with wxWidgets 2.9.x/3.x making the tracks list box 0
pixels high and expanding the notebook on the input tab expand
arbitrarily.
mmg input tab: refactor all border spacers
ChanageLog update
mmg: use SetSizerAndFit() instead of SetSizer() everywhere