Setup paste also disable mouse

Paste using primary select, helpful in case of Vim compiled without X
Add '[ob', ']ob', and 'cob' mappings for bg switching

Added three mappings to allow easy switching between dark and light
backgrounds. After setting the background, the current color scheme is
reloaded, to allow color schemes to adapt to the changed background.

See issue #58.
Add option toggle for 'virtualedit+=all'