Fix #13140: Early/Late Bound related ICEs.

The problem was that we need to apply the substitution, so that the
formal lifetime parameters get replaced with (unifiable)
free-lifetimes that can actually be fed into the constraint solver.

Also, refactor code os that substitution for `check_item` and
`check_method`, moving both down the control flow into `check_bare_fn`.

----

Finally, there was another (similar) spot where we needed to
substitute early-bound lifetimes when invoking an object method of a
trait.
Fix Repr impl for method::Candidate to include the method_ty.
Add test using early-bound lifetimes in trait generic parameters.
verify-grammar path to rust.md

When calling

   make verify-grammar

rust.md cannot be found, because the
path to rust.md is missing.

The path is set to:

   $(D)/rust.md

This can only be tested, when llnextgen is installed.

Signed-off-by: Jan Kobler <eng1@koblersystems.de>
verify-grammar keyword crate

When calling

   make verify-grammar

or when llnextgen is not installed:

   python2.7 src/etc/extract_grammar.py <src/doc/rust.md

an error is reported by extract_grammar.py that the

keyword "crate" is not defined.

This patch adds the keyword "crate" to the grammar in rust.md.

Signed-off-by: Jan Kobler <eng1@koblersystems.de>
verify-grammar llnextgen

When calling

    make verify-grammar

a lot of errors are reported by llnextgen.

Only simple errors like:

  missing semicolons,
  missing single quotes,
  usage of parentheses instead of squared brackets or
  usage of single quote instead of double quote

are fixed by this patch.

This can only be tested, when llnextgen is installed.

Signed-off-by: Jan Kobler <eng1@koblersystems.de>
Used inherited mutability in lexer::Reader.
De-@ TokenTree.
De-@ NamedMatch.
De-@ IdentInterner.
Remove a RefCell from pprust::State.
install: Verify that installed compiler runs

Another sanity check. Can be disabled in `install.sh` via `--disable-verify`
and `configure` with `--disable-verify-install`.
install: Explicitly delete the manifest during uninstall. Misc cleanup
install: Fix string formatting in an error
install: Extract function for creating absolute paths and reuse it
install: More error handling
Register new snapshot
dist: Tweak the OSX pkg installer

This performs a few touch-ups to the OSX installer:

* A rust logo is shown during installation
* The installation happens to /usr/local by default (instead of /)
* A new welcome screen is shown that's slightly more relevant
auto merge of #13157 : pnkfelix/rust/fsk-iss13140, r=nikomatsakis

r? @nikomatsakis

Fix #13140

Includes two fixes, and a semi-thorough regression test.

(There is another set of tests that I linked from #5121, but those are sort of all over the place, while the ones I've included here are more directly focused on the issues at hand.)
auto merge of #13170 : eddyb/rust/syntax-cleanup, r=alexcrichton

Removes all Cell's/RefCell's from lexer::Reader implementations and a couple @.