Improve some Win32 ctrl keybindings

Similar to #2166, this tries to get Win32 bindings feeling a more native for me.

* [x] `ctrl-home` should go to the beginning of the file
* [x] `ctrl-end` should go to the end of the file
* [x] `ctrl-delete` should delete the *next word*, not the previous word. i've used this for a long time, but i had to find some proof to make sure it wasn't something i just customized for myself. Here's a [reference](http://blogs.msdn.com/b/saraford/archive/2007/09/21/did-you-know-ctrl-delete-deletes-the-preceding-word-and-ctrl-backspace-deletes-the-proceeding-word.aspx) to back up that ctrl-delete should delete the following word and not the previous one.
* [x] `ctrl-pageup` goes to next tab
* [x] `ctrl-pagedown` goes to previous tab