Improves the style of some examples.

* Compacts all imports in a single line.
* Cleans whitespace before colons.
* Uses cmd abbreviation for command line enums.
* Replaces if/elif/else chain with case.

examples/cross_todo/nimrod_backend/backend.nim

@@ -2,10 +2,7 @@
 #
 # Most procs dealing with a TDbConn object may raise an EDb exception.
 
-import db_sqlite
-import parseutils
-import strutils
-import times
+import db_sqlite, parseutils, strutils, times
 
 
 type