contributing: wrap lines for readability

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Makefile.in: simplify logic for CFG_VER_HASH

git log -1 --pretty=format:'%H' is a very convoluted way of saying git
rev-parse HEAD.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
auto merge of #6952 : artagnon/rust/contributing-wrap, r=bstrie

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
.mailmap: tolerate different names, emails in shortlog

Write a conservative .mailmap as an example for contributors to write
their preferred names/ email addresses to.  This patch makes no
assumptions about the same author using different email addresses, and
only collects cases where the full-name of the person is spelt
differently for the same email address.  Verify with:

  $ git shortlog -se | cut -f 2 | cut -d\< -f 2 | sort | uniq -d

It only assumes that the author prefers the full-name that appears
dominantly, by number of contributions.

For the purposes of merging, a strictly alphabetical ordering is
advised.  See MAPPING AUTHORS section of git-shortlog(1) to understand
the format of this file.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
add renaming and sctable funs
change to newer macro escape mechanism, using uints in more places
comments & whitespace
parser comments
removed obsolete reference to purity
rename repr to name
just use TLS interner
removed some interner fields
interner just uses uints, not idents with syntax context
token_to_ident takes argument by reference
remove unused cx's
rand example fixup
remove interner from tt_reader
remove interner field from string_reader
removed unused imports (and one unused argument)
remove unused get_ident_interner's