[expr.prim.req] Applying wording fixes.

Join paragraphs to eliminate unnecessary single-liners.
Various formatting fixes.
[various] change "abbreviated function" to "abbreviated function template".
[expr] Update the list of unvevaluated operands in p8.
[expr.prim.req] Add a note to ad hoc constraints.

Also fix a broken reference.
[dcl.spec.auto] adjust editing marks
[expr.prim.req] Applying wording fixes.
Merge pull request #67 from Blzut3/master

Intro fixes
Merge pull request #66 from jicama/master

[various] change "abbreviated function" to "abbreviated function templat...
Merge branch 'master' of https://github.com/cplusplus/concepts-ts
[expr.prim.req] Editorial wording change.
[dcl.spec.auto] change marks for example
[expr.prim.req] Factor "always fail" conditions out of
specific constraints.
[expr.prim.req] Update example.
[dcl.spec.auto] more change markers
[expr.prim.general] Add auto nested-name-specifier.
[dcl.spec.auto] auto implies abbreviated function template.
[expr.prim.req] Reworking example.
[expr.prim.req] Remove unnecessary wording.
[dcl.spec.auto] allow auto anywhere in the declared type.
Merge branch 'master' of https://github.com/cplusplus/concepts-ts