Modify 'edit' command to depend on UI state

[ianyong]

Changes:

• Add generic edit command that returns one of the 2 specialised edit commands depending on UI state.
• Update test cases accordingly.
• Fix hash code for FinanceTracker.
• Fix addExpense and addIncome methods of ModelManager updating the wrong list.

Resolves #86.

[codecov-io]

Codecov Report

Merging #107 into master will increase coverage by 1.10%.
The diff coverage is 85.71%.

@@             Coverage Diff              @@
##             master     #107      +/-   ##
============================================
+ Coverage     67.99%   69.10%   +1.10%     
- Complexity      485      512      +27     
============================================
  Files            91       93       +2     
  Lines          1653     1738      +85     
  Branches        155      165      +10     
============================================
+ Hits           1124     1201      +77     
+ Misses          485      484       -1     
- Partials         44       53       +9     

Impacted Files	Coverage Δ	Complexity Δ
...s1_cs2103_w16_3/finesse/commons/core/Messages.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
...1s1_cs2103_w16_3/finesse/model/FinanceTracker.java	83.33% <0.00%> (+12.50%)	19.00 <0.00> (+2.00)
...021s1_cs2103_w16_3/finesse/model/ModelManager.java	87.67% <50.00%> (+12.32%)	29.00 <0.00> (+3.00)
...6_3/finesse/logic/commands/EditExpenseCommand.java	84.61% <84.61%> (ø)	8.00 <8.00> (?)
...16_3/finesse/logic/commands/EditIncomeCommand.java	84.61% <84.61%> (ø)	8.00 <8.00> (?)
...2103_w16_3/finesse/logic/commands/EditCommand.java	96.77% <100.00%> (+0.10%)	12.00 <3.00> (+2.00)
...6_3/finesse/logic/parser/FinanceTrackerParser.java	92.72% <100.00%> (-2.01%)	29.00 <0.00> (+3.00)	⬇️
...va/ay2021s1_cs2103_w16_3/finesse/ui/UiManager.java	0.00% <0.00%> (ø)	0.00% <0.00%> (ø%)
...a/ay2021s1_cs2103_w16_3/finesse/ui/CommandBox.java	0.00% <0.00%> (ø)	0.00% <0.00%> (ø%)
... and 9 more

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[zhaojj2209]

LGTM!

[yongping827]

LGTM