Previously closing NERDTree while two windows were showing the same
buffer would focus the first window, which was not necessarily the
previously active one.
Instead of obtaining the buffer ID of the previous buffer and
mapping that to the window ID (which is a 1:n mapping) we obtain the
unique window ID and focus the right window after closing NERDTree.
win_getid() and win_gotoid() are available from VIM 7.4.1557 but the
old behavior is used as a fallback if the two functions are not
available.
When g:NERDTreeChDirMode is 2, changing the tree root will change the working
directory as well. This change was silent because the wrong function was used to
make the switch. This commit uses a better function that echoes a message.
So :bprev was failing to jump back to the right buffer. I dont fully
understand this yet, but I'm fairly sure this is because there is a
magic <directory> buffer that we delete when creating a wintree :-/
Anyway, we are explicitly storing the prev buffer again - and updating
it when reusing treewins. It's worky, but there may be a superior way...
Add an API to allow custom "path filter callbacks" to be added.
Previously we allowed one path filtering function to exist called
`NERDTreeCustomIgnoreFilter`. This has been removed and replaced with an
API to allow any number of such functions to exist - via the new
`NERDTreeAddPathFilter()`
Add 2 new classes and move code into them from autoload:
* NERDTree. Each nerdtree buffer now has a NERDTree object that holds
the root node and will old other util functions
* UI. Each NERDTree object holds a UI object which is responsible for
rendering, getting the current node, etc
Still a fair few methods to sort through in autoload (many of which will
end up in the above classes) - need sleep though.
