Ignore location files.
Multiple changes in string handling, locations.

- Quote all instances of directories stored in variables (just in case).
- Split long lines.
- Put strings to be replaced in declaration of the OpenSMTPD directory
  variable, and the debian packages directory variable.  These strings
  will be replaced during installation with the contents of
  `location-OpenSMTPD` and `location-packages`, respectively.
Place proper locations in script, rename dir var.
Fix usage, un/installation instructions.