Build against vty 5.0.0
Merge master
Util: update for vty 5.1
Core: update for vty 5.1
Borders: udpate for vty5
Util: replace region_* functions from vty 4
Box: udpate for vty5
Edit: udpate for vty5
CheckBox: udpate for vty5
Table: update for vty5
DirBrowser: update for vty5
EventLoop: update for vty5
More updates for vty5
Update more vty5 API usage
Compile all executables with -threaded due to vty5 requirement
ListDemo: stale code
Limits: stale import
tests: due to word -> int change, use bounded generator
Core: use more readable accessors for display region fields
Core: oversized image check now only checks if both width and height are nonzero