Fix #839 (Generate documentation for built-in types and primitve operations)

Fix #839 (Generate documentation for built-in types and primitve operations)

This patch was originally by dinko.tenev@gmail.com, but I re-recorded
it in order to add a better log message.

The effect of this patch is to add entries for primitive types in the
documentation: Int#, Char#, etc. and to document the built-in
identifiers (seq, lazy, inline, unsafeCoerce#).