Fix Bug #548; BITCUT/BITCOPY/BITPASTE/BITPASTETOBITINDEX now throw errors.
Before, they showed a modal dialog boxes and threw a stopping error.
Also, if a BITMAPTURTLE has no bitmap, a message is printed to the commander, instead of showing a modal dialog box.
Authored by: david_costanzo 2020-10-25
Parent: [r5449]
Child: [r5451]