Minor changes:

* Add exclusion rules fro plugin 'indentline'.
* Add 'Alt/Meta' prefixed key mappings:
    Alt + H/L to navigate tabs.
Mapping changes.

* <M-Arrow Keys> to resize windows.
* <M-H/L> to switch tabs.
* Removed mappings to invoke :bnext and :bprev, ]b, [b dose better.
* Removed mappings to move tabs, never used them.
* Updated comment above those mapping definitions.