New rule for empty period

[Ducasse]

I saw some code like this: with the period after the first comment and it would be nice to have a rule spotting them.

phaserRate: anInteger
	"change phaserRate for the sound ".
	self dirtMessage add: 'phaserrate'; add: anInteger

[astares]

The "unnecessary characters found in method body" setting is unfortunately still off by default.

But we could extend the ReMethodSourceCleaner (which is already caring on a final dot and unnecessary whitespaces) to also care about an unnecessary dot behind a comment. The ReMethodSourceCleaner utility class is already used in ReCompactSourceCodeCritic / ReCompactSourceCodeRule