Adding script to fix MacVim bug with external displays

Sometimes after connecting or diconnecting my MacBook from external display(s), MacVim won't start again next time.

It happend some 5 times with me already. The workaround is to delete some files and restart OSX, as described here:
http://stackoverflow.com/questions/17537871/macvim-failed-to-start-after-connecting-to-a-extra-display-and-disconnected

So I thought it would be nice to have this at hand once and for all...