1. First, try to make it more portable to not-quite-standard
    systems (like Windows + MSVC) by not using alloca anywhere and by having
    configure look for `strcasecmp` vs `stricmp` and `strncasecmp` vs `strnicmp`, then
 2. Clean up some horrid interactions with bsearch by converting `blocktags[]` into
    an array of `struct kw`s and having `isopentag()` construct a `struct kw` and
    use that for searching instead of `malloc()`ing a buffer, making a null-terminated
    string, then comparing against that, and, finally
 3. Catch a horrible parsing bug where I didn't null-terminate html blocks during
    the blocking pass of the compiler, so at cleanup time I ended up double-freeing
    blocks and causing the program to dump core if I used anything other than
    `alloca()` inside `isopentag()`.