More enhancements and fixes

[zmre]

This includes the last pull request, but modified to strip the trailing slash twice.

Also included in this (and maybe these should be separate requests -- just let me know if I need to do this differently):

1. Fixed a bug where launching a project from the welcome screen did not properly set the local directory when nerdtree was enabled. Moving lcd before the nerdtree open fixed that issue.
2. Added the callbacks in when launching from the welcome screen so the environment can be configured for the new doc. Also run these before nerdtree to allow for NERDTreeIgnore configuration to be set. Note: the callbacks are only running when nerdtree is enabled and a new file is being opened.
3. I'm not a huge fan of the title changes. I added an option to leave the title alone. The default behavior remains the same.

[amiorin]

The callback signature is changed. I cannot merge your patch. Now it accepts also a dictionary and call invoke(title) on it. https://github.com/amiorin/vim-project/blob/master/autoload/project/config.vim#L74-L78