[PATCH] reduce the high memory consumption of the ShellDimScreen implementation

As I already mentioned in CORE-11422 we lost around 300kiloByte memory after bootup due to the introduction of ShellDimScreen in r72572 + r72573. It was not the implementation itself that caused this high jump, but the introduction of ATL into msgina. We loose this memory permanent (even before ShellDimScreen gets called). Therefore I put a week of work into porting it from ATL to plain C - same as msgina was before that commit, but still with a properly working ShellDimScreen.

Gain for gcc dbg I18N_LANG=de-DE based on r73557:
-300KB less memory after booting up the shell!
-iso filesize reduces a bit from 88.719.360 to 88.668.160
-msgina file-size drops from 388.096bytes to 301.056bytes -> only 78%

For stepwise review/comparison I decided to add 3 files here additionally:
0dimmedwindow-r73557.cpp point from where I started my work
1dimmedwindow-logicalChangesAndPorting.c
2dimmedwindow-Final_variableRenaming_and_indentation.c

And of course:
final.patch

For tests:
msgina-r73557-gcc-dbg-I18Nger-original.dll
msgina-r73557-gcc-dbg-I18Nger-patched.dll

That said: I love ShellDimScreen - I just love it even more when it's efficient.