refactor the Wiktionary extraction step, and...

add a file for the parsing step. It doesn't do anything yet, it just
contains the functions that were previously in the extraction step but
don't belong there.

The extraction step no longer writes millions of files into your
readers/ directory. It instead takes a directory name on the command
line, like other readers do, and outputs a sensible number of .jsons
files, like other readers do.

The contents of the JSON structures are not edges; they're the
semi-structured content of Wiktionary definitions, in need of further
parsing.
begin a Grako parser for Wiktionary
WIP: Wiktionary semantics
Semantics seem to work for translation sections

A bit slow, though.
indicate dependency on grako
regenerate parser
Remove the parser from git; it should be generated
WIP on definition parsing, before revising the grammar

Most whitespace is significant, it turns out.
Got significant whitespace working.

Definitions no longer have spaces where they don't belong, and do have
spaces where they do belong. Some text values may need to have spaces
stripped, later.
Minor fixes to syntax; update the comments
Fix semantics of templates with no args
Simplify the syntax tree for definitions
Parsed translations contain plain text, not LinkedText
Added some fancy template parsing, but keyword args aren't working
fix named arguments and etymology semantics
Sorta fix links with the language name after the hash
Add docstrings and refine some rules
remove an old assertion
Semantic rules for link sections
work around inconsistent behavior of @ inside +