Docs: Added info about case insensitive section and key names in configuration.

Signed-off-by: matematik7 <domen.ipavec@z-v.si>
Modules: Values tree structure and module init.

Created rpi_module_value_t structure that will be used for the tree of function to get all values in a module.

Made module_init function that creates module, initializes it and reads its configuration from modules.conf.

Signed-off-by: matematik7 <domen.ipavec@z-v.si>