Prune trailing whitespaces from code and documentation

They are redundant in all pruned cases and sometimes even create some
problems, e.g., when one tries to jump through paragraphs in vi.

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

Changelog.rst

@@ -122,7 +122,7 @@ OfflineIMAP v6.5.2 (2012-01-17)
 
 * Some sanity checks and improved error messages.
 
-* Revert 6.5.1.1 change to use public imaplib2 function, it was reported to 
+* Revert 6.5.1.1 change to use public imaplib2 function, it was reported to
   not always work.
 
 * Don't fail when ~/netrc is not readable by us.
@@ -280,7 +280,7 @@ Changes
 * Refresh server capabilities after login, so we know that Gmail
   supports UIDPLUS (it only announces that after login, not
   before). This prevents us from adding custom headers to Gmail uploads.
-  
+
 Bug Fixes
 ---------
 
@@ -338,7 +338,7 @@ New Features
 * When a message upload/download fails, we do not abort the whole folder
   synchronization, but only skip that message, informing the user at the
   end of the sync run.
- 
+
 * If you connect via ssl and 'cert_fingerprint' is configured, we check
   that the server certificate is actually known and identical by
   comparing the stored sha1 fingerprint with the current one.
@@ -437,7 +437,7 @@ Notes
 -----
 
 This was a very active rc1 and we could expect a lot of new fixes for the next
-release. 
+release.
 
 The most important fix is about a bug that could lead to data loss. Find more
 information about his bug here:
@@ -588,7 +588,7 @@ I'd like to thank reporters who involved in this cycle:
   - Pan Tsu
   - Vincent Beffara
   - Will Styler
-  
+
 (my apologies if I forget somebody) ...and all active developers, of course!
 
 The imaplib2 migration looks to go the right way to be definetly released but