Reworked a few issues in the python build script so that compilation

and link errors would be more self-evident.
  Now, link errors in the _cantera.so build will register with
the python layer, because a python exception is raised. This will
propagate into the Makefile causing make to prematurely stop the
build process, because one of its commands has come back with a
non-zero exit status. This causes the "make all" command to return
a non-zero exit status, so that the entire make command comes to a
halt, which is the desired behavior.

Cantera/python/Makefile.in

@@ -50,6 +50,7 @@ win: _winbuild
 #
 _build: $(SRCS) $(LIB_DEPS) Makefile setup.py
 	touch src/pycantera.cpp 
+	/bin/rm -f _build
 	(CXX="@CXX@"; export CXX; CC="@CXX@"; export CC; @PYTHON_CMD@ setup.py build)
 	echo 'ok' > _build
 

Cantera/python/setup.py.in

@@ -90,7 +90,10 @@ if buildPython >= 2:
                             ],
               )
     except:
-        buildPython = 1
+        if buildPython == 3:
+          buildPython = 1
+        else:
+          raise 'Error encountered while building or installing the Cantera python modules!'
     
         
 if buildPython == 1: