Convert WebArchiver module to shell around archiver
This reduces code duplication; now I have only one canonical codebase for archiving URLs.
+New module which parses and dumps URLs to a file for use by archiver…
Allows rate-limiting of requests; see file headers.
Made WebArchiver plugin more parallel (gwern).
Plugins: hlint and import cleanup (gwern).
Modified WebArchiver plugin to make Alexa requests (gwern).
Changed plugin names, made them all work.
+ Removed redundant 'Plugin' from their names.
+ ImgTeX plugin needed an update.
+ All plugins included in gitit.cabal.