tests: enabled custom project root directory
tests: fixed overwriting parent variable in recursive conf generator
dirscanner: better method for searching the project root

implemented a search function which looks for smroot files
if one is found, it's directory is set as smroot
conf/expr: added missing util.path include for smpathifrel
bulider: removed useless util.path.rppath include
tests/builder: using new method for aquiring smroot
tests/builder: specified valtypes for 'build' and 'use'
tests/builder: removed default settings for pre/postbuild
tests/builder: remove development lock of user variables
tests/path: improved argument order of testcase
util/path: heavily simplified methods for abs/rel/smpath