Improve indentation in CMake files

Some users might want to perform vertical alignment of arguments passed to CMake functions / macros, e.g.

set(FRUITS APPLE
           BANANA
           CHERRY)

If one inserts a newline after the line with CHERRY), the cursor is placed as so (with | denoting the cursor position):

set(FRUITS APPLE
           BANANA
           CHERRY)
        |

It'd be nice if Qt Creator would instead indent based on the location of the matching opening parenthesis, so that the cursor would be placed on the same column as the start of the set() call.