Flask and Django template debugging

[DonJayamanne]

Fixes #1172
Fixes #1173

This pull request:

• Has a title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Has unit tests & code coverage is not adversely affected (within reason)
• Works on all actively maintained versions of Python (e.g. Python 2.7 & the latest Python 3 release)
• Works on Windows 10, macOS, and Linux (e.g. considered file system case-sensitivity)

[codecov]

Codecov Report

Merging #1313 into master will decrease coverage by 49.42%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           master    #1313       +/-   ##
===========================================
- Coverage   71.08%   21.66%   -49.43%     
===========================================
  Files         269      269               
  Lines       12383    12391        +8     
  Branches     2190     2196        +6     
===========================================
- Hits         8802     2684     -6118     
- Misses       3449     9656     +6207     
+ Partials      132       51       -81

Impacted Files	Coverage Δ
src/client/debugger/ProxyCommands.ts	0% <0%> (-100%)	⬇️
src/client/linters/linterInfo.ts	5.4% <0%> (-94.6%)	⬇️
src/client/common/idDispenser.ts	7.14% <0%> (-92.86%)	⬇️
src/client/language/tokenizer.ts	4.43% <0%> (-92.3%)	⬇️
src/client/common/process/proc.ts	8.23% <0%> (-91.77%)	⬇️
src/client/formatters/lineFormatter.ts	7.75% <0%> (-91.45%)	⬇️
src/client/language/characterStream.ts	4.41% <0%> (-91.18%)	⬇️
...nittests/common/testVisitors/resultResetVisitor.ts	9.37% <0%> (-90.63%)	⬇️
...nt/unittests/common/services/testResultsService.ts	4.28% <0%> (-90%)	⬇️
...lient/unittests/unittest/services/parserService.ts	9.09% <0%> (-88.64%)	⬇️
... and 201 more

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