Make consistent use of wp_malloc and sizeof

- Calls to wp_malloc no longer take a type, but a size, consistent with
  the malloc library call
- Casts removed from calls to malloc
- Type name removed from diagnostic messages due to type change
  specified above
- sizeof expressions now prefer the variable name over the type name
  where possible
- Extraneous parentheses removed from sizeof expressions
Improve documentation and remove wp_rmalloc

- Remove wp_rmalloc from wp_memory.w
- Fix incorrect memory allocation in wp_test:
  - malloc(sizeof wp_suites[i]) should have been the pointer to
    wp_suites[i]
- Documentation now consistent with updated code. References to
  wp_rmalloc removed
  - Sections renamed from |wp_memory.c| and |wp_memory.h| to
    |wp_memory|
  - Improved clarity throughout documentation
  - Extraneous cruft removed