initial commit of constants
add constants plugin
add note and static flags (not used)
fix .pc so that cmake will substitute value
remove not available docdir
remove .h and doc folder
remove wrong recommended plugins
remove header file
initial commit of noresolver
add new exceptions for tools
validate plugin contracts better
fix noresolver
shell tests

give more info why test failed
constants is not a rw_storage
provide status why backend is not validated

+ improve constness
fix some constants + other bugs
fix contract from noresolver
fix contract from uname
give status about backend validation when it failed