CONTRIBUTING.md: fix path to run_astyle.bat
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.
Build.bat: Add loop for signing. In case of failure we will know exactly which file is the problem.

Based on XhmikosR's ideas.
typo
cosmetics
reduce variable scope
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
Losslessly compress png images with https://github.com/subzey/zopfli-png and then with PNGGauntlet.