nvidia-settings: fix spelling

Most of these typos are in comments, but a few are in strings visible in the
compiled application.

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Fix some misspellings noticed by lintian

Signed-off-by: Aaron Plattner <aplattner@nvidia.com>
Merge branches 'fix-spelling' and 'contrib'

Conflicts:
	src/Makefile