add toggle methods, refs #4
update autoloads file
let the neotree be equal to the neotree-show
modify doc
add neotree-test module
test for toggle
rename variables
rename util functions
rename path functions
rename buffer methods
rename global functions
add neotree-buffer
rename window functions
modify el headers
When toggle occured, keeps the same root dir as last time.
hide *NeoTree* when select buffer
upgrade to 0.1.5
Merge pull request #6 from jaypei/dev

升级到 0.1.5