Adjust CMakeLists.txt and .def: add _d postfix onto jansson_d.lib/dll

Had to remove the "LIBRARY" line from jansson.def, which was optional,
and was overriding CMake's desire for a specific name.
Implemented a decode option to only decode numbers to reals and never integers
Added a simple test for the JSON_DECODE_NO_INT option
Merge pull request #120 from paulharris/mine_pre_2.5

Adjust CMakeLists.txt and .def: add _d postfix onto jansson_d.lib/dll
Renamed flag to JSON_DECODE_INT_AS_REAL and added documentation
Changed :versionadded for JSON_DECODE_INT_AS_REAL docs
Using jsonp_strtod instead of casting to double to catch double overflow
Merge pull request #123 from jjwchoy/decode-ignore-int

Implemented a decode option to only decode numbers to reals
Fix indentation in docs
Tweak the JSON_DECODE_INT_AS_REAL test introduced in #123

Only run the imprecision part if json_int_t is long long, otherwise
the imprecision cannot be tested against json_int_t.

Also, convert the double value to json_int_t before checking the
imprecision, because otherwise the json_int_t is converted to double
and the imprecision happens in the "wrong direction".
Prevent unused-variable warning