Imexam removes installed binaries during cleanup

[olebole]

Imexam tries to remove the system installed xpa binaries (xpaaccess and such) and libraries during setup.py clean (and fails if they are protected from removal). This is quite dangerous, since it may leave people with a unusable system if they don't install the new package: https://github.com/spacetelescope/imexam/blob/ebea0bb0393f1f71b244ccc30742bea6148c6eb1/setup.py#L208-L221

These binaries and libraries also may be installed by other software (like DS9), which may get unusable when these files are removed.

[sosey]

doh, gah. sorry, this is an oversight on my end....I had moved the binaries elsewhere. let me fix...