#1008 RTRIM() has no form to trim only CHR(0) or only CHR(32)

[Jeff Marshall]

Found this test file for investigating the behaviour trimming CHR(0) and CHR(32) using RTRIM, probably from around Mar 2024. And was probably around the time of this forum post: https://www.freebasic.net/forum/viewtopic.php?p=302678#p302678

Not actually sure if this was seen as a bug or only that the behaviour needs to be explained more.

The test file compares fb rtlib behaviour with some possible alternate implementations of the function.