add ithread support, const a table
Merge pull request #17 from bulk88/c_optimizing

add ithread support, const a table
t/96_interop.t: broke with LEHMANN/JSON-XS-3.01
t/96_interop.t: add JSON::PP test

JSON::PP cannot be used anymore, since JSON broke the JSON::PP API.
It is now named JSON::BackportPP but provides JSON::PP.
3.0101 release: fixed booleans for JSON 2.9 and JSON-XS-3.01 interop

add INTEROP with JSON and JSON::XS pod section.
add more interop tests

we just to know the JSON version beforehand so we can prepare our internal boolean representation
add PERL_NO_GET_CONTEXT

also removed unrefed var warning in encode_rv()
3.0102 release

- MANIFEST: added t/96_interop.t
- Document deprecated functions
- Change booleans interop logic relying only on JSON-XS-3.01, independent on JSON now.
Types::Serialiser::Boolean for JSON-XS-3.01 interop

 - Change booleans interop logic (again) for JSON-XS-3.01
   Check now for Types::Serialiser::Boolean refs (#18 clintongormley)
   to avoid allow_blessed for JSON-XS-3.01 booleans.
- add t/52_object.t from JSON::XS
- add .gitignore
3.0103: backport allow_tags, decode_tag, FREEZE/THAW callbacks from JSON-XS-3.01

- support JSON::XS extensions for OBJECT SERIALISATION: allow_tags, FREEZE/THAW
- improve encode_hv HE sort on stack < 64 or heap to avoid stack
  overflows (backported from JSON-XS-3.01). do not use alloca.
- fix t/52_object.t
- fix t/96_interop.t if JSON is not installed
t/z_leaktrace.t added, #19 not repro yet
fix C89 builds
Free MY_CXT.sv_json on exit