fixe int32_t definition for VC11

int32_t is nowhere in msvc, so the version check could be even removed
snprintf definition is needed here, too
Fix C89 compat needed by MSVC
Fixes for Infinity and NaN

Although JSON RFC does not support NaN or Infinity
as numeric values ECMA 262 section 9.8.1 defines
how to handle these cases as strings
in strick mode, number must not start with 0
Merge pull request #88 from weltling/master

Several MSVC fixes
Merge pull request #89 from ayanes/master

Support NaN and Infinity
Merge pull request #90 from remicollet/issue-strict

in strick mode, number must not start with 0
Minor spell check.