[mkrel.sh] Rewrite the release build script.
[mkrel.sh] Rewrite the release build script.

 * mkrel.sh now considers the HEAD in git repository as the main source
   to build from (instead of the local directory tree, which can be
   polluted by many temporary files or uncommited modifications.

 * Only two ZIP packages are now generated. Source package corresponding
   to the 'git archive' command and binary, which contains 32-bit and
   64-bit prebuilt DLLs, import libraries, examples and also generated
   documentation.

mity/mctrl,mity/mctrl,mity/mctrl,mity/mctrl