Update: simplify and rework string functions

Update: simplify and rework string functions

The rip and append functions are functionally identical.
Remove the rip function.

With the rip functions gone, the rip_trim functions are renamed to rip.
This way "rip" functions operate like a theoretical append_trim function, but with fewer words.

Make the string functions use start and stop ranges instead of lengths.
This eliminates the needs for the partial functions.

Add new nulless functions that check for and remove nulls from source strings while transferring them to the destination string.
This allows for converting the strings that may have nulls to nulless strings such that they can be used in null-sensitive functions such as those found in the standard C libraries.

Make sure the utf_string functions match correspond to the string functions.