Move list_sep to powerline.lint.checks

It is the only place where it is needed.

powerline/lint/checks.py

@@ -10,12 +10,15 @@ from powerline.lib.unicode import unicode
 from powerline.lint.markedjson.markedvalue import MarkedUnicode
 from powerline.lint.markedjson.error import DelayedEchoErr, Mark
 from powerline.lint.selfcheck import havemarks
-from powerline.lint.context import list_sep, list_themes
+from powerline.lint.context import JStr, list_themes
 from powerline.lint.imp import WithPath, import_function, import_segment
 from powerline.lint.spec import Spec
 from powerline.lint.inspect import getconfigargspec
 
 
+list_sep = JStr(', ')
+
+
 generic_keys = set((
 	'exclude_modes', 'include_modes',
 	'exclude_function', 'include_function',

powerline/lint/context.py

@@ -14,7 +14,6 @@ class JStr(unicode):
 
 
 key_sep = JStr('/')
-list_sep = JStr(', ')
 
 
 def list_themes(data, context):

powerline/lint/spec.py

@@ -9,7 +9,6 @@ from copy import copy
 from powerline.lib.unicode import unicode
 from powerline.lint.markedjson.error import echoerr, DelayedEchoErr
 from powerline.lint.selfcheck import havemarks
-from powerline.lint.context import list_sep
 
 
 class Spec(object):
@@ -77,7 +76,7 @@ class Spec(object):
 				context_mark=context_mark,
 				problem='{0!r} must be a {1} instance, not {2}'.format(
 					value,
-					list_sep.join((t.__name__ for t in types)),
+					', '.join((t.__name__ for t in types)),
 					type(value.value).__name__
 				),
 				problem_mark=value.mark