3.7 Backwards compatibility with old configuration file syntax

The syntax described herein is new for version mtools-3.0. The old line-oriented syntax is still supported. Each line beginning with a single letter is considered to be a drive description using the old syntax. Old style and new style drive sections may be mixed within the same configuration file, in order to make upgrading easier. Support for the old syntax will be phased out eventually, and in order to discourage its use, I purposefully omit its description here.