bookmarks: rename readcurrent to readactive (API)

Today, the terms 'active' and 'current' are interchangeably used throughout the
codebase in reference to the active bookmark (the bookmark that will be updated
with the next commit). This leads to confusion among developers and users.
This patch is part of a series to standardize the usage to 'active' throughout
the mercurial codebase and user interface.

mercurial/bookmarks.py

@@ -106,13 +106,12 b' class bmstore(dict):'
         for name, node in self.iteritems():
             fp.write("%s %s\n" % (hex(node), encoding.fromlocal(name)))
 
-def readcurrent(repo):
-    '''Get the current bookmark
-
-    If we use gittish branches we have a current bookmark that
-    we are on. This function returns the name of the bookmark. It
-    is stored in .hg/bookmarks.current
-    '''
+def readactive(repo):
+    """
+    Get the active bookmark. We can have an active bookmark that updates
+    itself as we commit. This function returns the name of that bookmark.
+    It is stored in .hg/bookmarks.current
+    """
     mark = None
     try:
         file = repo.vfs('bookmarks.current')

mercurial/localrepo.py

@@ -416,7 +416,7 b' class localrepository(object):'
 
     @repofilecache('bookmarks.current')
     def _bookmarkcurrent(self):
-        return bookmarks.readcurrent(self)
+        return bookmarks.readactive(self)
 
     def bookmarkheads(self, bookmark):
         name = bookmark.split('@', 1)[0]