Add some functions.

Hi. I added some functions to the dired plugin.
I was wondering if you could consider to merge your useful plugin and this.

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Added functions are that:

- `Preveiw` : Preveiw a selected file or directory. 
- `Bookmark` : Add Selected directory to Bookmark or Project directories, and go to them with quick panel called `GotoAnywhere` in this code.  
- `Jump to line` : Jump to the line of file's or dir's name with quick panel in the current directory.

All codes of these functions are written in __dired.py__ , and I didn't change the original code in it except for NORMAL_HELP.
I also added key-bind, command, and scopes in dired.tmLanguage.

I confirmed working this functions on Windows7 64bit & Sublime Text 3(Build 3059) and Fedora20 64bit & Sublime Text 3(Build 3059).

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Thank you for reading it through.