Fix tcl compress/uncompress error handling and doc

[michaelortmann]

Found by: michaelortmann Patch by: michaelortmann Fixes:

One-line summary: Fix tcl compress/uncompress error handling and doc

Additional description (if needed): compression functions were already returning different return values but for case movefile() fails COMPF_SUCCESS was returned This PR fixes that and and the doc that belongs to it

Test cases demonstrating functionality (if applicable):