This allows adding or removing plugins w/o overriding the whole list of
default plugins, which makes it easier to upgrade when new default plugins
are added.
for other types of search engine plugins if wanted, and also opening up a
lot of new possibilities for other kinds of plugins later
some notable changes along the way:
- lots of new hook types: cgi, render, delete
- wrapper files fixed to support config strings with newlines in them
- HEADERCONTENT in page template useful for plugins. Probably needs to be
expanded to more such for other places plugins might want to add content.
- remove unnecessary wrappers field from config info stored in wrappers
kept in mind during this are a) to reduce load time for common cases like
cgi and post-commit and b) make the code easier to navigate.
This also modularises RCS support to the extent that it should be possible
to drop in a module for some RCS other than svn, add a switch for it, and
it pretty much just work.
High chance I missed an edge case that breaks something, this is only
barely tested at this point.
checkoptions() that can be used to set defaults for this and other options
based on existing options.
Also involved some cleanups to how gen_wrapper is used.