Set PYTHONPATH for nrnivmodl-core workflow (#199)

 - when cmake is run, PYTHONPATH is setup correctly and nmodl
    with sympy can be used.
  - for nrnivmodl-core workflow, PYTHONPATH needs to be set
    in the makefile so that nrnivmodl is self contained.

Author: pramodk

CMakeLists.txt

@@ -124,6 +124,7 @@ if (ENABLE_NMODL)
     else()
         set(ENV{PYTHONPATH} "${nmodl_PYTHONPATH}:$ENV{PYTHONPATH}")
     endif ()
+    set(NMODL_PYTHONPATH $ENV{PYTHONPATH})
 endif ()
 
 

extra/nrnivmodl_core_makefile.in

@@ -135,6 +135,7 @@ $(OBJS_DIR)/%.obj: $(MODC_DIR)/%.ispc | $(OBJS_DIR)
 # Build ispc files with mod2c/nmodl
 $(mod_ispc_files): $(MODC_DIR)/%.ispc: $(MODS_PATH)/%.mod | $(MODC_DIR)
 	@printf " -> $(C_GREEN)MOD2C$(C_RESET) $<\n"
+	PYTHONPATH=@NMODL_PYTHONPATH@ \
 	MODLUNIT=$(datadir_mod2c)/nrnunits.lib \
 	  $(mod2c_install_bin) $< -o $(MODC_DIR)/ @nmodl_arguments_ispc@
 
@@ -144,6 +145,7 @@ $(mod_ispc_c_files): $(MODC_DIR)/%.cpp: $(MODC_DIR)/%.ispc
 # Build cpp files with mod2c/nmodl
 $(mod_c_files): $(MODC_DIR)/%.cpp: $(MODS_PATH)/%.mod | $(MODC_DIR)
 	@printf " -> $(C_GREEN)MOD2C$(C_RESET) $<\n"
+	PYTHONPATH=@NMODL_PYTHONPATH@ \
 	MODLUNIT=$(datadir_mod2c)/nrnunits.lib \
 	  $(mod2c_install_bin) $< -o $(MODC_DIR)/ @nmodl_arguments_c@