Add the configuration dialog for post processing configuration options.
Only enables the config button when the shader options available to it
Remove the duplicated IniFile::ParseLine in PostProcessing.cpp
Just make the one in IniFile static and use it instead
Add a GetTime() function to the PP shaders API.

This can be used to know the movement of time in shaders for fancy effects.
Split the PostProcessing class in to two.
One is the PostProcessingShaderConfiguration which is configuration only.
The second is the PostProcessingShaderImplementation which contains the pure virtual functions required for an implementation to implement.
Adds a comment to PostProcessingShaderConfiguration::LoadShader.