Improvements to the SQlite-based local status folder

* Do not inherit LocalStatusSQLiteFolder class from the plaintext
    one.

  * Use some functions already in BaseFolder in both, plaintext and
    sqlite classes.

  * Add a saveall method. The idea is that saveall dumps the entire
    messagelist to disk, while save only commits the uncommited
    changes. Right now, save is noop for sqlite, and equivalent to
    saveall for plaintext, but it enables to be more clever on when we
    commit to disk in the future.

Signed-off-by: Eygene Ryabinkin <rea@codelabs.ru>

offlineimap/folder/LocalStatus.py

@@ -29,6 +29,7 @@ class LocalStatusFolder(BaseFolder):
     def __init__(self, name, repository):
         self.sep = '.' #needs to be set before super.__init__()
         super(LocalStatusFolder, self).__init__(name, repository)
+        self.root = repository.root
         self.filename = os.path.join(self.getroot(), self.getfolderbasename())
         self.messagelist = {}
         self.savelock = threading.Lock()
@@ -47,14 +48,6 @@ class LocalStatusFolder(BaseFolder):
     def getname(self):
         return self.name
 
-    # Interface from BaseFolder
-    def getroot(self):
-        return self.repository.root
-
-    # Interface from BaseFolder
-    def getsep(self):
-        return self.sep
-
     # Interface from BaseFolder
     def getfullname(self):
         return self.filename
@@ -178,6 +171,11 @@ class LocalStatusFolder(BaseFolder):
 
 
     def save(self):
+        """Save changed data to disk. For this backend it is the same as saveall"""
+        self.saveall()
+
+    def saveall(self):
+        """Saves the entire messagelist to disk"""
         with self.savelock:
             file = open(self.filename + ".tmp", "wt")
             file.write((self.magicline % self.cur_version) + "\n")