fixed BUG-115 move to existing paths can contain dashes

BUGs

@@ -9,5 +9,3 @@ BUG-109: add mich force override, removed it, then re-added it, then rebuild DB
 BUG-114: when moving files, the offered similar dirs include those from other paths:
     - when we change the sel_rp (and icon), should also change offered similar dirs 
     - AND its showing 'Import/Camera_Uploads/...' - is this a path issue in files.py / GetExisting* or?
-BUG-115: GetExistingPaths chomps suffix when it contains '-'
-    - '2021/20211231-new-years-eve' -> prefix='2021/20211231-' & suffix='new'

files.py

@@ -809,7 +809,8 @@ def GetExistingPathsAsDiv(dt):
             continue
         if not first_dir:
             ret +=", "
-        bits=dir.rel_path.split('-')
+        # maxsplit 1, means bits[1] can contain dashes
+        bits=dir.rel_path.split('-',maxsplit=1)
 
         ret+= '{ '
         ret+= '"prefix":"' + bits[0] + '-", '