default view agenda in GUI
edit undo
Merge branch 'parser'
Merge branch 'UI'
add done for undo redo functions
edit undo for done
add window into command handler
Completed tasks are gray
Completed tasks are gray
solve refresh issue
update portion of help to html
Merge branch 'UI'
remove stackOverflow error
solve view agenda problem
add up to 10 task compat for interpreter
add persistent add and delete functions
add zombiemail declaration
Deadline task color from yellow to orange
Merge branch 'UI'
updated update and done
Merge remote-tracking branch 'origin/master'

Conflicts:
	src/zombietask/ZombieTaskCommandHandler.java
fixed error of dates in location and tags