move FilterBase in filters module

compress/filter_base.py

-class FilterBase:
-    def __init__(self, verbose):
-        self.verbose = verbose
-
-    def filter_css(self, css):
-        raise NotImplementedError
-
-    def filter_js(self, js):
-        raise NotImplementedError
-
-
-class FilterError(Exception):
-    """This exception is raised when a filter fails"""
-    pass

compress/filters/__init__.py

+class FilterBase:
+    def __init__(self, verbose):
+        self.verbose = verbose
+
+    def filter_css(self, css):
+        raise NotImplementedError
+
+    def filter_js(self, js):
+        raise NotImplementedError
+
+
+class FilterError(Exception):
+    """This exception is raised when a filter fails"""
+    pass

compress/filters/closure/__init__.py

 import subprocess
 
 from compress.conf import settings
-from compress.filter_base import FilterBase, FilterError
+from compress.filters import FilterBase, FilterError
 
 
 class ClosureCompressorFilter(FilterBase):

compress/filters/csstidy/__init__.py

@@ -4,7 +4,7 @@ import tempfile
 
 from django.conf import settings
 
-from compress.filter_base import FilterBase
+from compress.filters import FilterBase
 
 BINARY = getattr(settings, 'CSSTIDY_BINARY', 'csstidy')
 ARGUMENTS = getattr(settings, 'CSSTIDY_ARGUMENTS', '--template=highest')

compress/filters/jsmin/__init__.py

 from compress.filters.jsmin.jsmin import jsmin
-from compress.filter_base import FilterBase
+from compress.filters import FilterBase
 
 
 class JSMinFilter(FilterBase):

compress/filters/uglifyjs/__init__.py

 import subprocess
 
 from compress.conf import settings
-from compress.filter_base import FilterBase, FilterError
+from compress.filters import FilterBase, FilterError
 
 
 class UglifyJSCompressorFilter(FilterBase):

compress/filters/yui/__init__.py

 import subprocess
 
 from compress.conf import settings
-from compress.filter_base import FilterBase, FilterError
+from compress.filters import FilterBase, FilterError
 
 
 class YUICompressorFilter(FilterBase):