Improvements big and small:
- Instead of assuming that classes not found in any of the "import"
  clauses are from the "java.lang" package, the current file's package
  is now resolved and used.
- When getting information from cache, the cache entry is moved to the
  front so that it's less likely to be removed when the cache is full.
- A command javap-cache-drop-matching was introduced to remove all
  cache entries of classes matching user-provided regexp.
- Some variables were renamed.