DolphinTool: add missing spaces in help text

[Tilka]

No description provided.

[Dentomologist]

Not technically part of the scope of this PR, but a few other things that might be worth changing:

• --help descriptions aren't capitalized, while everything else is.
• Some descriptions don't end with periods.
• Under header --help, the --block_size description wraps all the way to the left edge of the window instead of the left edge of the description column like everything else. I'm not sure yet what causes that, or if it's just on my end somehow.

[Tilka]

I get the same weird wrapping of the block size description. I looked at it for a bit but I'm too tired to understand optparse::str_format() right now.