Fix variable scope

Global scope must be used for variables that are not specific to one buffer,
and `b:curr_file` has to be reset for each buffer.

Closes: #31

Consolidated filename functionality. Closes #30

Added OS X and Google Chrome auto refresh with applescripts

Use vim-markdown-preview as the name for all html generated files

Merge pull request #24 from rpoddighe/master

Correctly handle spaces in local filepaths

Correctly handle spaces in local filepaths

Added xdg-open support

Check if global flags exist before setting them

Handle space in filepath names; Fixes #19

Added variable to remap ctrl-p

Fixed image rendering markdown path

Added GitHub markdown to image preview mapping

Merge pull request #11 from oshybystyi/support-for-github-flavoured-md

Added support for github flavoured markdown

Added support for github flavoured markdown

Made temp file and toggle global variables; updated README

Merge pull request #10 from gmerzu/master

Supports global variable to set a browser

Supports global variable to set a browser

Fixed remove temp file bug

Moved common variables up; interoperable browsers;
Fixed unix background bug

Updated plugin mapping comments