make examples work and help texts more consistent and readable.

This pull request should make: 
 * the CLI command examples work
 * CLI help texts more consistent 
 * and readable

This pull request changes: `core/modules/utils/fakedom.js` `formattedTextContent` handler.
Since it is only used to create command line output, there should be no side effects. 

`pre` and `li` now create an indentation with 4 spaces, which imo makes the help texts much more readable. The formatting in the TW output is not affected. 

see the difference with: 

```
node tiddlywiki.js --help     ... new
tiddlywiki --help              ... old if tiddlywiki is installed globally
or
node tiddlywiki.js --help server
tiddlywiki --help server
...
```
I think it would be unusual to use both a colon and a dash. Perhaps the big problem with the output of `--help` is the double spacing of the commands, and maybe it would look better if we could use tabs to bring the descriptions into line with one another?