instantiation -> specialization in [refwrap]

To match the wording of http://cplusplus.github.io/LWG/lwg-active.html#2106 (The wording of 2106 is taken from here, but we decided to use the term "specialization".
Fix typography of "C." (spacing)
[expr.prim.general] Use code font for ~.
[cpp] Fix font of # in non-directive.
[gram] Don't convert one space to two after a `.` or `!` in the grammar.
These do not mark the end of a sentence.
Use a consistent size and position for all tildes.
Replace all '\sim's with '\~'s, to give more consistent formatting for ~s.
Merge pull request #348 from tkoeppe/typography1

Fix typography of "C." (spacing)
[basic.lookup.classref] Use code font for `~`.
Fix to 2013-09 LWG Motion 7:

[comparisons] Fix incorrect application of N3789 to the working paper:
  - Add 'constexpr' to
      std::equal_to<>::operator()
      std::not_equal_to<>::operator()
      std::greater<>::operator()
      std::less<>::operator()
      std::greater_equal<>::operator()
      std::less_equal<>::operator()
  - Reorder 'bool constexpr' to 'constexpr bool' in
      std::logical_or<T>::operator()
      std::logical_and<T>::operator()
      std::logical_not<T>::operator()

Also fixes 14882:2014 DIS JP 08, fixes 14882:2014 DIS JP 09, fixes #291.
JP 06: [dcl.constexpr] Remove incorrect example.

Also fixes #370.
JP 14: [thread.sharedtimedmutex.class] Reformat synopsis for consistency
with nearby subclauses. Add "// blocking" comment systematically to
lock() on all timed mutex classes.

Fixes #374.
JP 16: [thread.sharedtimedmutex.class] Add missing 'or' at end of
bullet.

Fixes #375.
[multiset.cons] Add missing parameter type.

Fixes #189.
[complex.ops] Reorder 'bool constexpr' to 'constexpr bool' for
consistency.
JP 11: [thread.mutex.requirements.general] Remove outdated sentence.

This sentence directly contradicts several other portions of the
standard, and does not reflect the intended meaning.
[lex.ppnumber] Reorder grammar rule to make the similarities and
differences between the digit separator and non-digit-separator
productions more obvious.
JP 04: [lex.icon] Consistently order descriptions of integer literals in
increasing radix order.

Fixes #368.
[expr.new] Avoid "heap allocation"

The term "heap allocation" is not normatively defined, and the term "heap" has other meaning in the standard. Here "heap allocation" is typical implementation details, likely close to "free store". To clarify the intent, it would be better never used at all, even in an example.
Merge pull request #380 from FrankHB/patch-3

[expr.new] Avoid "heap allocation"