Support unicode whitespace

[jnwatson]

All Python \s (Unicode whitespace + ASCII separators) is now treated as
whitespace in Storm. This has a potential for very minor backwards
incompatibility, as previously unicode whitespace characters were
treated like normal characters.

Update lark version requirements; use its new use-regex feature.

Make minor improvements in some of the regular expressions in the storm
grammar.

[codecov]

Codecov Report

Merging #1812 into master will decrease coverage by 1.63%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1812      +/-   ##
==========================================
- Coverage   96.12%   94.49%   -1.64%     
==========================================
  Files         139      139              
  Lines       26761    26671      -90     
==========================================
- Hits        25725    25202     -523     
- Misses       1036     1469     +433     

Flag	Coverage Δ
#linux	94.49% <100.00%> (-1.64%)	⬇️
#linux_replay	66.00% <100.00%> (-0.71%)	⬇️

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

Impacted Files	Coverage Δ
synapse/lib/parser.py	97.44% <100.00%> (-0.86%)	⬇️
synapse/tools/feed.py	0.00% <0.00%> (-82.80%)	⬇️
synapse/lib/encoding.py	33.33% <0.00%> (-51.59%)	⬇️
synapse/lib/gis.py	48.57% <0.00%> (-51.43%)	⬇️
synapse/models/dns.py	49.15% <0.00%> (-50.85%)	⬇️
synapse/lib/modelrev.py	57.14% <0.00%> (-34.29%)	⬇️
synapse/lib/coro.py	69.31% <0.00%> (-29.55%)	⬇️
synapse/cryotank.py	69.94% <0.00%> (-21.39%)	⬇️
synapse/models/geospace.py	80.82% <0.00%> (-16.44%)	⬇️
synapse/models/telco.py	85.22% <0.00%> (-14.78%)	⬇️
... and 29 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 418b85e...3506773. Read the comment docs.