Add interface definition for NIL value type
Add implementation for ws_value_nil_init()
Add CMakeLists.txt entry
Add method ws_object_lock_try_read()
Add method ws_object_lock_try_write()
Comment out a non-working section

What was happening is that the code currently searched for a given CRTC/monitor
pair. However, this was not working, so I removed this part of the code.
Fixed linked list implementation

I had the implementation of a linked list backwards. This replaces it with a
sane version. I also added more log messages that also document success cases.
Added more log messages
Merge pull request #97 from matthiasbeyer/add-value_nil

Add implementation for value_nil type
Merge pull request #120 from TheNeikos/fix-framebuffer_creation

[WIP] Fix framebuffer creation
Add initialisation of shared memory
Merge pull request #119 from neithernut/add-object_trylock

Add object trylock
Merge pull request #116 from neithernut/add-shm-initialisation

Add initialisation of shared memory
Add test files
Add cmake module for finding check framework
Add CMakeLists.txt files for test build-env
Ignore .test files
Enable adding sources and libraries to tests
Add objects/set.{c,h} files and CMakeLists.txt entry
Add initial interface definition