[Development] Coding style: space after comma

[Edward Welbourne]

I notice that our coding style [0] doesn't actually say out loud that we
expect a space after each comma (and none before).  Its sole mention of
comma is that it goes at a line-end, unlike operators at line-start, on
a continued line.  Yet the Qt code-base is mostly consistent about this
and I've seen other reviewers ask for it, so I understand it to be part
of our de facto style.  I also favour it.

[0] https://wiki.qt.io/Qt_Coding_Style

I propose to follow (under "Whitespace") the list item

  * Surround binary operators with spaces

with

  * Leave a space after each comma

Any objections, or improved wordings ?

(I omit "none before" in light of the still-controversial constructor form,

  Derived:Derived(Type arg, Mode um, Form ent)
  : Base(arg)
  , mem(um)
  , ber(ent)
  {}

discussed some time ago, IIRC inconclusively.)

	Eddy.