Ian Edington 1e6798717a Added markdown foldtext function ...

Addresses an issue metioned in tpope/vim-markdown#10 of adding a
foldtext function.

- Displays == and -- headers as # and ##
- Use markdown header style instead of '+--' to show nesting

Given the example of

    This is Header One
    ==================
    This is Header Two
    -----------------
    ### This is Header Three
    This is a normal line

Instead of:

    +--  6 lines: This is Header One-----------------------------
    +---  4 lines: This is Header Two----------------------------
    +----  2 lines: ### This is Header Three---------------------

You get:

    # This is Header One [6 lines]-------------------------------
    ## This is Header Two [4 lines]------------------------------
    ### This is Header Three [2 lines]----------------------------

2017-05-01 15:03:38 -04:00

..

markdown.vim

Added markdown foldtext function

2017-05-01 15:03:38 -04:00