Change templating engine to Jinja2

[sl1-1]

Resolves Issue #4

[lgtm-com]

This pull request introduces 7 alerts when merging f07d549 into 123a690 - view on LGTM.com

new alerts:

• 3 for Wrong number of arguments in a call
• 2 for Unused local variable
• 2 for Unused import

[codecov-io]

Codecov Report

Merging #751 into master will increase coverage by 4.05%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #751      +/-   ##
==========================================
+ Coverage   67.62%   71.67%   +4.05%     
==========================================
  Files         156       35     -121     
  Lines       12643     1896   -10747     
==========================================
- Hits         8550     1359    -7191     
+ Misses       4093      537    -3556

Impacted Files	Coverage Δ
libweasyl/libweasyl/html.py	0% <ø> (-42.11%)	⬇️
libweasyl/libweasyl/legacy.py	61.53% <0%> (-38.47%)	⬇️
libweasyl/libweasyl/compat.py	80% <0%> (-20%)	⬇️
libweasyl/libweasyl/defang.py	87.5% <0%> (-5%)	⬇️
libweasyl/libweasyl/flash.py	91.52% <0%> (-3.39%)	⬇️
libweasyl/libweasyl/text.py	93.56% <0%> (-1%)	⬇️
weasyl/commishinfo.py
weasyl/test/web/conftest.py
weasyl/test/test_profile.py
... and 84 more

---

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[lgtm-com]

This pull request introduces 7 alerts when merging 56cd55c into 123a690 - view on LGTM.com

new alerts:

• 3 for Wrong number of arguments in a call
• 2 for Unused local variable
• 2 for Unused import

[lgtm-com]

This pull request introduces 4 alerts when merging f0c5ff4 into 123a690 - view on LGTM.com

new alerts:

• 2 for Unused local variable
• 2 for Unused import

[lgtm-com]

This pull request introduces 4 alerts when merging 461d211 into 123a690 - view on LGTM.com

new alerts:

• 2 for Unused local variable
• 2 for Unused import

[lgtm-com]

This pull request introduces 4 alerts when merging c96fc5c into 123a690 - view on LGTM.com

new alerts:

• 2 for Unused local variable
• 2 for Unused import