Merge pull request #5 from jswiergo/build-fixes

Fixes broken unit tests (#4)
Merge pull request #6 from jswiergo/dynamic-structs

More flexible structs + configurable  sizes of nodes
fixed CMakeLists.txt files
more compile fixes
tweak unit test to work with mingw. Still needs fixing.
oops. typo in av_log_set_level
created WindowsBuild.txt instructions.
Updated README and fixed typos in WindowsBuild.txt
updated instructions to install CMake
Renamed WindowsBuild.txt to WindowsBuild.md.
Hopefully will render better on github.
Formmated the windows build instructions to look good on github.
Merge master