This commit increases the value buffer to 11 characters - this is
technically what it should be to allow for large negative integers
(i.e., 2.4 billion plus the sign character).
Additionally corrected the types for 'H' (horizontal offset) and 'V'
(vertical offset) - these are supposed to be i32 versus u32.
Added some extra tests to test all of this stuff as well.
I've also added a few more tests to help track these cases.
