Use default location ~/.cycache when cython cache is set to True.

Cython/Build/Dependencies.py

@@ -670,7 +670,7 @@ def cythonize(module_list, exclude=[], nthreads=0, aliases=None, quiet=False, fo
     if 'include_path' not in options:
         options['include_path'] = ['.']
     if 'common_utility_include_dir' in options:
-        if 'cache' in options:
+        if options.get('cache'):
             raise NotImplementedError, "common_utility_include_dir does not yet work with caching"
         if not os.path.exists(options['common_utility_include_dir']):
             os.makedirs(options['common_utility_include_dir'])

Cython/Compiler/Main.py

@@ -481,6 +481,11 @@ class CompilationOptions(object):
         options['compiler_directives'] = directives
         if 'language_level' in directives and 'language_level' not in kw:
             options['language_level'] = int(directives['language_level'])
+        if 'cache' in options:
+            if options['cache'] is True:
+                options['cache'] = os.path.expanduser("~/.cycache")
+            elif options['cache'] in (False, None):
+                del options['cache']
 
         self.__dict__.update(options)