Don't allow spaces before headers in nav mappings.

It breaks too often when you have code blocks with comments that
start with `#`, and no one uses spaces before headers.
Merge pull request #83 from cirosantilli/no-space-before-header

Don't allow spaces before headers in nav mappings.

Breaks too often when you have code blocks with comments that start with #.
Fix folding bug if folding disabled option is 0
Use get() instead of exists() in ftplugin/mkd.vim
Merge pull request #92 from y0t4/fix_if_folding_disabled_is_0

Fix folding bug if folding disabled option is 0
Make the default mappings buffer local

If mappings aren't defined as 'buffer local', they are defined in other
files too and this causes conflicts with mappings there.
Merge pull request #94 from bruno-/buffer_local_mappings

Make the default mappings 'buffer local'
Add HeaderDecrease, HeaderIncrease and SetexToAtx.