[COLOR] Explicitly cast int to float.

(Coverity CID 1227534 and 1227535)
[GRID] Fix invalidating column header cells.

(Coverity CID 1227536)
[TABLE] Fix mcTable_Create() to return the created table handle.

(Coverity CID 1227517)
[examples/ex_dllgetversion.c] Add missing FreeLibrary() on error paths.

(Coverity CID 1227518)
[HTML,IMGVIEW] Replace all InlineIsEqualGUID() with IsEqualGUID().

Instead we predefine __INLINE_ISEQUAL_GUID for release build.

The motivation is to avoid some false positives in Coverity scan
as InlineIsEqualGUID() usually uses some dirty hack.