load: Avoid unexpected behaviour in macro expansion

Macros can be dangerous if the inserted arguments are not properly
parenthesised. As macro expansion does a simple replacement, inserting
a certain expression can cause the evaluation order of the macro expression
to change.
load: Change buffer_pos to be a size_t

buffer_pos should be type size_t, because it's used to store the
current position in the read buffer. Also, it never can be negative.
Merge branch '2.3'

Closes #70.
Fix tutorial to use Github API v3

The v2 API will be shut down on May 1st 2012.

Fixes #65.
Merge branch '2.3'
jansson 2.3.1
Merge branch '2.3'

Conflicts:
	configure.ac
	doc/conf.py
	src/jansson.h
Check for missing args and envvars in run-tests.sh

Fixes #71.
Merge branch '2.3'
fix slight typo in json_pack apiref example

Fixes #73.
Merge branch '2.3'
fix slight typo in json_pack apiref example

Fixes #73.
Merge branch '2.3'
Support building on Windows

Jansson now builds correctly with Visual C++ Express 2010.
Add vs2010 solution and project
Fix build warnings under MinGW
Merge pull request #74 from rogerz/contrib

Add vs2010 solution and project, fix warnings under MinGW
Update the documentation to mention Visual Studio 2010 support
Bugfix: Changed all use of ssize_t to size_t.

ssize_t is only used in a test, and its comparing to a size_t variable.

Fixes #77.
Bugfix: must cast void* to do pointer math

Fixes #78.