Add more validation checks for block and room related functions

[schoolex]

closes #211
closes #205
closes #196

[teekoksiang]

Almost LGTM, some boundary cases need to be handled.

[codecov-io]

Codecov Report

Merging #219 into master will decrease coverage by 0.96%.
The diff coverage is 29.09%.

@@             Coverage Diff              @@
##             master     #219      +/-   ##
============================================
- Coverage     63.56%   62.59%   -0.97%     
- Complexity      619      621       +2     
============================================
  Files           110      110              
  Lines          2234     2275      +41     
  Branches        263      274      +11     
============================================
+ Hits           1420     1424       +4     
- Misses          708      738      +30     
- Partials        106      113       +7     

Impacted Files	Coverage Δ	Complexity Δ
src/main/java/seedu/address/MainApp.java	0.00% <0.00%> (ø)	0.00 <0.00> (ø)
...main/java/seedu/address/commons/core/Messages.java	0.00% <ø> (ø)	0.00 <0.00> (ø)
.../seedu/address/logic/parser/EditCommandParser.java	72.09% <0.00%> (-9.49%)	13.00 <0.00> (ø)
...rc/main/java/seedu/address/model/person/Block.java	72.72% <ø> (ø)	10.00 <0.00> (ø)
src/main/java/seedu/address/model/UserPrefs.java	65.26% <30.76%> (-25.51%)	22.00 <1.00> (+2.00)	⬇️
...a/seedu/address/logic/parser/AddCommandParser.java	85.18% <42.85%> (-14.82%)	5.00 <0.00> (ø)
src/main/java/seedu/address/model/person/Room.java	58.06% <100.00%> (ø)	14.00 <1.00> (ø)

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[teekoksiang]

Good job! LGTM.