Add command to edit meetings and prevent conflicting meetings

[sebastiantoh]

Closes #109, closes #111

Changes:

• Added command to update meetings: meeting edit INDEX [c/CONTACT_INDEX] [m/MESSAGE] [d/DATETIME] [du/DURATION]
• Added check for conflicting meetings whenever meeting is added / edited (note this
• Updated help window for meeting edit and reminder edit
• Updated test files which fails due to conflicting meetings
• Added a small note in user guide about how conflicting meetings will not be allowed to be added / edited
• Added section in user guide on meeting edit

Demo of meeting edit:

Demo of conflicting meetings:

[codecov-io]

Codecov Report

Merging #148 into master will increase coverage by 0.42%.
The diff coverage is 81.88%.

@@             Coverage Diff              @@
##             master     #148      +/-   ##
============================================
+ Coverage     74.30%   74.72%   +0.42%     
- Complexity     1163     1201      +38     
============================================
  Files           164      166       +2     
  Lines          3709     3846     +137     
  Branches        508      537      +29     
============================================
+ Hits           2756     2874     +118     
- Misses          775      784       +9     
- Partials        178      188      +10     

Impacted Files	Coverage Δ	Complexity Δ
.../address/logic/commands/meeting/DeleteCommand.java	100.00% <ø> (ø)	7.00 <0.00> (ø)
...address/logic/commands/reminder/DeleteCommand.java	100.00% <ø> (ø)	7.00 <0.00> (ø)
...u/address/logic/commands/reminder/EditCommand.java	88.73% <ø> (ø)	14.00 <0.00> (ø)
...ss/logic/parser/meeting/MeetingCommandsParser.java	55.55% <0.00%> (-6.95%)	5.00 <0.00> (ø)
src/main/java/seedu/address/model/Model.java	100.00% <ø> (ø)	6.00 <0.00> (ø)
...c/main/java/seedu/address/ui/MeetingListPanel.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
.../main/java/seedu/address/ui/ReminderListPanel.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...edu/address/logic/commands/meeting/AddCommand.java	76.47% <14.28%> (-16.13%)	11.00 <0.00> (ø)
...du/address/logic/commands/meeting/EditCommand.java	81.57% <81.57%> (ø)	13.00 <13.00> (?)
src/main/java/seedu/address/model/AddressBook.java	84.40% <85.71%> (+0.08%)	76.00 <5.00> (+5.00)
... and 8 more

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[hakujitsu]

LGTM besides the minor things pointed out!

Just an idea, I think it would be helpful to print the conflicting meeting to the user when the error is thrown!

[sebastiantoh]

LGTM besides the minor things pointed out!

Just an idea, I think it would be helpful to print the conflicting meeting to the user when the error is thrown!

Makes sense. Thanks for the suggestion, I've included the above!

[hakujitsu]

LGTM, merging now!