ignore keys when HUD is invisible
issue #15: add error report generator
fix crash caused by testing code in commit 796e0a0
conservatively separated render methods for HUD & base env. preparation for issue #7 and issue #6
issue #7: fixed scope implementation
issue #7: add cursor-attached scope and circular cursor for bare minimum desktop use
issue #9: shift to desktop mode if app is no longer running
include requirement and desktop feature in README
Merge branch 'develop'