Initial work on a critcl json parser based on json-c. Issues: many-json2dict has no C equivalent, nor the *2dict commands. Boolean is 0/1 vs true/false in C vs. Tcl, this should be fixable in the testsuite. Basics are working.
Integrated additional MI work on a Tcl_ObjType for lazier construction
of the Tcl strcutures from the json C structures.

Notes
- Modified the Tcl parser to return 0|1 for boolean values, to match
  the new C parser. Updated testsuite.
- Supplied my own definition of assert to fit in with Tcl (Tcl_Panic).
- Modified the C conversion of json null to match the Tcl parser, is
  now 'null', not the empty string.
- Changed Tcl_Dict* uses to equivalent Tcl_List* to keep the code
  usable for Tcl 8.4
- Moved the code handling the deferal/laziness into lazy_value2obj and
  applied it to array elements as well, not just object fields.
- Moved the variables in value2obj into the switch branches.
- Changed the Tcl_ObjType structure initialization to regular C.
  Code as provided (see ticket attachment json2.c) looked like some
  GCC-ism.

Open question
- Why does the json2string function not just generate the string rep,
  but takes the int.rep as well, shimmering the Tcl_Obj*. Seems to
  presume that the string generation is immediately followed by Tcl
  code forcing a shimmer anyway ?!

Reduced testsuite passes.
Implemented many-json2dict and validate over json-c.
Test cases for many-json2dict reactivated, passing.
New cases for validate, passing.

Should add test cases for invalid json input.
Moved the larger test cases and data into separate files, less quiting
that way. Added test case for the escape-able characters.

Added test cases for invalid json.

Shifted the json generating procedures to the common file, making them
shared between Tcl and C implementations.

Added a benchmark suite, using the test cases in the files as input.
Fixed buglets which slipped through in previous commit.
Small test simplification
Sort tests by name in the data arrays
Fix bug in json::dict2json. Nobody seems to have used this before.
Added synthetic benchmarks constructing larger json structures.
Switched validation from the C parser to a shared Tcl implementation, regexp based. It is consistently faster. No overhead creating ireelevant data structures is main suspected cause.
Finalized integration. Bumped to version 1.3.
Integrated work on a first C parser for JSON. json 1.3, tcllibc 0.3.11. See ticket [6efa4f571a].