added new options to implement different curves for conductance - psi(LWP)
changed leaf conductance curve implementation
changed defaults for non-standard stratum lwp-conductance curves
Update construct_stratum_defaults.c

fixed typo in new parameter curve name
fixed bug in use of new LWP-conductance curves
Merge branch 'newstrata'

Added new parameters to stratum default to allow for different forms of the lwp-conductance curve in jarvis