Support \u0000 - add size_t string lengths to API, load and dump \u000, etc.
Also:
  Steal strings during parsing for half the mallocs!
  Change all input-caused assertions to errors.  No crashes please, we're programmers.
dump \u sequences as upper case for readability (just like error messages)
expect "export" in test configs
document new null-friendly functions
Merge pull request #140 from chipdude/nuls

Support "\u0000" in strings