Merge pull request #455 from frank-dittrich/bleeding-jumbo

Bleeding jumbo
Fix typos in comments (run/repeats16.conf, run/repeats32.conf)
doc/OPTIONS: "-example ciphertext" added to --list=format-details

The documentation had not been updated when --list=format-details
has been extended.
Grammer fix in doc/EXTERNAL
In core doc files, use GNU-style double dashes for long option names

This is the syntax that is used in all core doc files.
The only exception: 2 examples in doc/EXAMPLES explaining that
the option names can be abbreviated.

For now, I didn't bother with all the Jumbo specific doc files.
But we should thing about adjusting these as well.
1,$s#-for=#-form=#g in run/DYNAMIC, because -for= is ambiguous

... since --fork= has been added.

I'd prefer to turn this into --format=, and adjust other option names
as well.
But since I didn't write that document, I went for the minimal change
fixing th error.