Parser: Support explicit matchers, critical bug fixes

[tony]

Parser:

• Git scp-style URLs: Fix detection detect of scp style URLs with .git prefixes
• Fix critical bug where matchers were being applied as variable not annotations
• Fix pattern_defaults
• Base tests: Rename Location to URL
• Tests and modules: Rename _location to _url

[codecov]

Codecov Report

Merging #386 (efe929f) into master (0f2d30b) will increase coverage by 0.28%.
The diff coverage is 90.69%.

@@            Coverage Diff             @@
##           master     #386      +/-   ##
==========================================
+ Coverage   73.34%   73.63%   +0.28%     
==========================================
  Files          26       26              
  Lines        2165     2185      +20     
==========================================
+ Hits         1588     1609      +21     
+ Misses        577      576       -1     

Impacted Files	Coverage Δ
libvcs/parse/svn.py	93.87% <60.00%> (-1.96%)	⬇️
libvcs/parse/hg.py	95.91% <66.66%> (-2.00%)	⬇️
libvcs/parse/base.py	88.23% <100.00%> (+6.98%)	⬆️
libvcs/parse/git.py	100.00% <100.00%> (+1.58%)	⬆️
tests/parse/test_git.py	100.00% <100.00%> (ø)
tests/parse/test_hg.py	100.00% <100.00%> (ø)
tests/parse/test_svn.py	100.00% <100.00%> (ø)

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