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".
[expr.const] Add missing 'const' to examples invalidated by N3598.

Fixes CWG1683.
[class.mem] Format definition of 'layout-compatible' as a definition,
add it to the index, and unify spelling of this index entry across the
three places where it is defined.
Add 1ex of vertical space between numbered paragraphs.
[dcl.dcl] Split the introduction of *declaration*, *simple-declaration*, and
*attribute-declaration* into three separate paragraphs, rather than having a
single paragraph spanning a whole page.
Remove paper.
Remove unused definitions of terms 'formal argument', 'actual argument', and
'actual parameter'. Unify uses of 'formal parameter' and 'parameter' to all use
the vastly more common term 'parameter' and remove the definition of 'formal
parameter'.
Tighten the words we use in "Throughout this [sub]clause" wording
to introduce a set of requirements for template arguments based
on their names, and make these paragraphs consistent.
Fix vertical whitespace around grammar definitions and bullets.
Remove trailing blank lines at ends of grammar productions.
US-1 Add numbering for bullets. Bullets are numbered within the surrounding
paragraph or bullet, not within the relevant bulleted list, so that numbers are
unique. The main text formatting is unchanged; bullet numbers are placed in the
left margin, just like paragraph numbers.

Also fixes #177.
[memory.general] Add missing `<` character to C header name.
Parenthesize bullet numbers to make it more obvious that text after the bullets
is part of the preceding paragraph.
[class] Move paragraph breaks to improve vertical whitespace.
[ratio.syn] Use digit separators to make large numbers more readable.
Fix 'tokens not allowed' warnings when building PDF.
[rand] Use modern spelling of \frac and \binom to remove LaTeX warning.
[toc] Make room for page numbers >= 1000 in table of contents.
[ratio.syn] Fix formatting of codeblock with digit separators.
Remove bullet numbering for bullets outside of any paragraph.