typo
cosmetics
reduce variable scope
CONTRIBUTING.md: fix path to run_astyle.bat
AppSettings.cpp: move ADDCMD define outside of the function and remove the undef.
VSFilter: move the AboutDlg version to a new define and use that
AboutDlg.cpp: use the MPC_VERSION_ARCH define
solution files: remove RARFileSource from Lite builds.

We don't link it so there is no need to build RARFileSource.
Also fix the platform for Lite builds even if it's unused.
Losslessly compress png images with https://github.com/subzey/zopfli-png and then with PNGGauntlet.
Build.bat: Add loop for signing. In case of failure we will know exactly which file is the problem.

Based on XhmikosR's ideas.