add change listener to the command box, should be able to implement the command suggestion feature
trying to implement switching of tabs by pressing TAB, not completed
Added HelpManager
Fixed some small bugs
trying to implement the help text
Improved on HelpManager
Improved on HelpManager
Further improve on HelpManager
Revert "Further improve on HelpManager"

This reverts commit e4ab1ca2f096081701975c729b7d65ef0b638c7b.
Merge remote-tracking branch 'origin/AutoHelp' into UI
Merge remote-tracking branch 'origin/AutoHelp' into UI

Conflicts:
	src/ticker/logic/HelpManager.java
Merge remote-tracking branch 'origin/AutoHelp' into UI
Editted some commands in HelpManager
edit the help page
Merge branch 'UI'
fix the bug of displaying current time
support display for searching free slot, free slots will be marked in green