KBoot image support

Found a bug in segment writing; will update soon.

Bug fixes and added support for KBoot images, which are minimal sized ATRs that include a boot header and an executable but no directory structure.

• Added context menu to segments list to save segment
• Fixed menu item segment parser that wasn't being set correctly
• Added KBoot disk image support from atrcopy 2.0
• Fixed disassembler references to segment data to properly handle IndexedByteSegments
• Fixed map editor overlay command where mouse released on same tile as pressed: no last command in batch = error
• Added log file recording on all platforms