Extract database and model object

Transform former structs containing the database and the model
from common.{c.h} to objects of the library. This provides a
higher level API for developer wanting to use libuproc.
Add missing files for database and model objects
add TODO comment about version-info
clang-format ALL the code

Conflicts:
	detailed.c
exit if clang-format returns nonzero
Add context pointer to error handler
Merge remote-tracking branch 'origin/devel' into error_handler_data

Conflicts:
	common.c
	libuproc/error.c