Use a regular expression to try to detect unresolved links.

The naive grep'ing for ][ produces too many false positives from
code blocks using arrays.
Include link to symas.com/mdb for LMDB keyword.
Print warning if unexpanded macros are encountered.
Use search instead of match to find unresolved links.

Warn for unexpanded macros.
If function has no attributes, replace macro with empty line.

Returning an empty list of lines from a macro function indicates
error and leaves the macro unexpanded for diagnostics.
Using function_attributes for functions with no parameters is not
wrong, so allow it by returning a single empty line.
New design and layout
- CSS changes
- some HTML div nesting/naming changes for new layout
Hide github edit link for now
Header and footer changes
Merge pull request #115 from michaelclelland/master

Updated design and layout
Accurate matching of optional space before opening link.
Don't post-process printable pages.