Discuss clang-format options.

This isn't meant to be merged, but rather, be a discussion about which
options people want to use. I've added comments next to each formatting
option that clang-format supports and that we specify. Many of them are
fairly obvious choices and some of the settings I'm ignoring for now,
either for future discussion or because they are for fine tuning later and
not important at the moment.

For things I want to call out as potentially contentious, I'll have the
comments start with **'s.
I prefer braces on the next line for all of if/switch/while/do and function definitions but I found in for instance the nested if's associated with choosing an icon for the treeWidgets in dlgTriggerEditor.cpp that the vertical space taken up by just opening and closing braces reduced what active code could be shown on one screenful. So when I was poking around in a local copy I got into removing the braces around single line "then" or "else" statements on at least the innermost if() but always left a blank line after the (indented) else "code" - which cut down 3 out of 4 lines per if().

It IS easier to cut and paste clumps of code if the '{' around that code '}' are vertically aligned which is probably why I prefer it.  Something about as we read left to right our attention focuses on the start of the line - but that is just a thought and may not be backed up by any actual, erm, evidence!