Set up Jinja whitespace control in Babel mapping

[andreyv]

The lstrip_blocks environment parameter affects Jinja parsing mode, see pallets/jinja#748. Hence we need to use the same whitespace control parameters as in the actual CMS code.

Fixes #1096.

I also changed the mapping file to use the conventional INI file syntax for better source highlighting.

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This change is 

[codecov]

Codecov Report

Merging #1130 (7c5e31e) into master (7f77a52) will increase coverage by 0.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1130      +/-   ##
==========================================
+ Coverage   63.50%   63.55%   +0.05%     
==========================================
  Files         232      232              
  Lines       17028    17028              
==========================================
+ Hits        10813    10822       +9     
+ Misses       6215     6206       -9     

Flag	Coverage Δ
functionaltests	47.46% <ø> (+0.06%)	⬆️
unittests	44.12% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
cms/service/ProxyService.py	65.62% <0.00%> (-1.57%)	⬇️
cms/db/filecacher.py	77.41% <0.00%> (-0.65%)	⬇️
cms/db/base.py	87.12% <0.00%> (ø)
cms/grading/Job.py	90.90% <0.00%> (+0.45%)	⬆️
cms/service/EvaluationService.py	73.13% <0.00%> (+0.49%)	⬆️
cms/service/workerpool.py	66.11% <0.00%> (+0.55%)	⬆️
cms/server/admin/handlers/base.py	70.62% <0.00%> (+0.66%)	⬆️
cms/server/contest/handlers/contest.py	87.37% <0.00%> (+0.97%)	⬆️
cms/io/triggeredservice.py	87.87% <0.00%> (+1.01%)	⬆️
cms/server/contest/handlers/tasksubmission.py	48.63% <0.00%> (+1.09%)	⬆️
... and 2 more

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