Document and apply code formatting style

Several details of code formatting are inconsistent at the moment.

The first step should be to document the desired style on the wiki; then we can clean up the main text by applying the documented style.

Here are some items I noticed repeatedly:

• template <class T, class U = T> struct Foo<T, U>
  • space between template <
  • no space in template specializations, Foo<T, U>
  • space around = in U = T
• f(a, b , c)
  • space after comma, not before
  • no space before the leading parenthesis in function call expressions
• Generally, spaces around binary operators except for comma.
• Space before leading parenthesis in control structures (for, while, if).
• No spaces between closing template brackets: Foo<Bar<T>>. I think there's a separate issue open for this already, but it should go into the style guide in any case.

I think many of those rules are fairly easy to check globally with grep, and so the cleanup shouldn't be terribly difficult or protracted.

Start by documenting the listed formatting rules on the wiki, including the rule about adjacent closing template brackets. Then inspect the main text and use grep to identify inconsistent formatting, apply the documented style, and verify that the cleanup covers the listed cases without duplicating the separate issue's work.