replace a warning with an assert.

the warning was a temporary because there was a bug in the code that would have caused this assertion to fail. Since that bugs was fixed, i replaced it with an assert.
Add a test case for bug #22215
CodeBlocks project update
Fix compilation with SDL2.

Commit cec386ad35a1d5ddb9b721d3c66abc091e8ca68f broke compilation due to
removing an required include.
Fix Clang documentation warnings.

The string //<< is seen as documentation comment instead of normal
comment.
Mark some functions static.
Update the UMC IDE developer manual
Merge pull request #214 from aquileia/VC_update

Update VC project
Reintroduce <algorithm> include