1. my interpretation of subject sequence definition was wrong. adjust
parser to conform to the standard.
2. some code for handling tail overflow case was missing (forgot to
finish writing it).
3. typo (= instead of ==) caused ERANGE to wrongly behave like EINVAL
this fixes a number of bugs in integer parsing due to lazy haphazard
wrapping, as well as some misinterpretations of the standard. the new
parser is able to work character-at-a-time or on whole strings, making
it easy to support the wide functions without unbounded space for
conversion. it will also be possible to update scanf to use the new
parser.
sadly the C language does not specify any such implicit conversion, so
this is not a matter of just fixing warnings (as gcc treats it) but
actual errors. i would like to revisit a number of these changes and
possibly revise the types used to reduce the number of casts required.
