Speeds up font compilation by around 200%

Cython is used to compile some hot paths into native Python extensions.
These hot paths were identified through running ufocompile with the hotshot
profiler and then converting file by file to Cython, starting with the "hottest"
paths and continuing until returns were deminishing. This means that only a few
Python files were converted to Cython.

Closes #23
Closes #20 (really this time)

misc/pylib/booleanOperations/exceptions.py

@@ -0,0 +1,21 @@
+from __future__ import print_function, division, absolute_import
+
+
+class BooleanOperationsError(Exception):
+    """Base BooleanOperations exception"""
+
+
+class InvalidContourError(BooleanOperationsError):
+    """Rased when any input contour is invalid"""
+
+
+class InvalidSubjectContourError(InvalidContourError):
+    """Rased when a 'subject' contour is not valid"""
+
+
+class InvalidClippingContourError(InvalidContourError):
+    """Rased when a 'clipping' contour is not valid"""
+
+
+class ExecutionError(BooleanOperationsError):
+    """Raised when clipping execution fails"""