add variables to define xplor installation path and xplor version

note 1. this could be improved by auto detecting these variables by
doing a which pyXplor

Conflicts:
	xcamshift/src/cython/setup.py
add link args to point to python lib
target atom ids argument to Force Factor calculator becomes CDSVector

this is because creating and using memoryview objects inside a nogil
section is painful
correct a linkage problem shared vector symbols were not being found
Fast_force_factor_calculator calc takes a CDSVector[int] on the stack
remove a bug and use CDSVector more for active_target_atom_ids
remove target_atom_ids for signature of calc_shifts in sub_potentials
add a mechanism to instantiate required templates
_calc_factors now takes target atom ids as a CDSVector

not we are using a translation function during the transition cdef
CDSVector[int] int_memory_view_as_cds_vector(int[:] data) which will
disapear when we are finished
_native_active_target_atom_ids becomes a pointer
_native_active_target_atom_ids now controls active atom id updates
_active_target_atom_ids is now a CDSvector[int]
calc_energy now takes active_target_atom_ids as a CDSVector[int]
energy calculator split into a base and implementation class

this is because force factor calculator was receiving a redundant
calEnergy methods
_shift_cache and _ensemble_shift_cache are now decalred as cdef objects
make Observed_shift_table a cdef class and get_native_shifts and test
make get_native_shifts nogil
Observed_shift_table was caching native shifts which will not work...

added a test to show native shifts are no longer cached
update energy calculator split into a base and implementation class

update to  b7cc6a5106336d7f2f9efd82bc86de7fd38143aa shift_calculator.pyx
rather than Cython_shift_calculator.pyx was commited ;-)
remove data from body of CDSSharedVectorFloat it should be in the header 

this was an omission from the commit
4706610e06e45e296878fd00e7afefdb5bde0431