Simplify Json tests
Add handle tests

* Modified handle.c and type.c to use new naming scheme
* Remove unnecessary types (char, long)
* Cleanup type.c/type.h -- no longer auto-generated

TODO: more handle tests
Handle tests for numeric types, and some fixes

Fun stuff:
* (-0x80000000 > 0) == true
  This is because 0x80000000 is given type uint32_t. The "-" then
  negates it, but that doesn't change the value.
* -0x8000000000000000LL has a similar issue
* Signed/unsigned comparison often does the wrong thing!
  (uint32_t)100 > (int16_t)-5 == false
Add voidp, var, charp tests.

Also add nb_var_buffer* functions.