Markup consistency & nits.

Fix typo in a C code example:  KeyError is spelled PyExc_KeyError in C; the
"K" is upper case!

Some index entries.

On function signatures, always use parameter names.  Make return types match
what's in the header files.  When the return type is a pointer, always omit
the space between te type name and the "*"; leaving it in results in

	type * func(..)

and having two spaces there just looks terrible.