Control File: continuation field cannot start with a period

The continuation capability allows you to enter a value for a field on multiple lines. However, anywhere in a Control file you cannot have an empty line, so it looks like it is not possible to enter an empty line in a Description or some other field (it is mostly likely only useful for descriptions, though.)

Debian offers a way to add an empty line: you start a line with a space add one period and nothing else. That line is considered completely empty (and it is given that way to users of the Control File API.) If any characters are added after that period, however, an error is generated.

The reason for the error is because at some point Debian may add support for additional capabilities using that syntax, but for now you just cannot start any continuation field with a period followed by a space and then other characters (i.e. " . abc"). In case of a Description this should not be a problem because you can always move the text around so the period is not at the beginning of the line.

Note that in Debian this is supposed to only be for the Description field, but we did not see the usefulness to having it for that capability in the first place. If it causes too much havoc then we will remove this check.

VALIDDescription: A Real Package System for MS-Windows
 Here starts the long description, followed by an empty line
 Another paragraph after the empty line.
INVALIDDescription: An Invalid Description
 There are the wonderful features of wpkg:
 . Create Packages
 . Install Packages
 . Remove Packagess
 In other words, the full monty of managing packages for an entire complex system.