Add 'C' command as alternative for Bdelete.

Needs vim-bbye plugin.
bufexplorer: pick next file, override defaults.
TCD + NERDTree integration: use TCD everywhere.

NERDTree has a few ways to change the current directory; explicitly by
pressing 'cd' or implicitly if the g:NERDTreeChDirMode setting is used.

Overriding NERDTree's "changeToDir" method allows to cover both.
Add Tcd command as well as TCD.