Couple more tweaks to html rendering:
a) SubX definitions no longer link redundantly to themselves. This long-standing
issue turns out to be tractable to solve for SubX files since the syntax
is so simple.
b) Fix links to SubX definitions in other directories. I forgot that I
have to always generate tags from the directory of the file being linkified.
c) Fix link colors. Before we lost all syntax highlighting for functions
and Globals. Now they maintain their colors, just add an underline.
a) Switch to a light background.
b) Linkify calls in .subx files.
c) Keep all colorization in the Vim colorscheme, get rid of hacky special-cases
in update_html.
We're going to lean back into the experiment of commit 4179 back in Jan.
If we delete memory it's up to us to ensure no pointers into it survive.
Since deep-copy depends on our refcounting infrastructure, it's gone as
well. So we're going to have to start watching out for pointers shared
over channels.
Each line number also gets an anchor name, but I'm not hyperlinking them for now
because I don't want to encourage bookmarking these links just yet. They aren't
permalinks because every revision may change what's at any given line number.
