add function reset() to c++ lbfgs

add tests as well
Merge pull request #49 from js850/lbfgs_reset

add function reset() to c++ lbfgs
clean up lbfgs a bit.

inline some functions and remove using statements for lbfgs.h
Merge branch 'master' of github.com:pele-python/pele
move functions into class body to avoid double definition errors
remove warnings from c++ tests

remove warnings about comparison between signed and unsigned integers by
using 1u instead of 1
add some test for rigid body systems

fix a few minor issues
Merge pull request #50 from kjs73/lowest_eig_namespace

move functions into class body to avoid double definition errors
improve EXPECT_NEAR_RELATIVE