Add syntax::print::pprint::view_item_to_string

… similar to the existing `item_to_string`.

There may be more missing like this.
plugin-guide: nicer creation of the parser
Register new snapshots

This in theory enables uncommenting IndexMut implementations, but upon doing so
the compiler immediately segfaulted in stage1, so I'll leave those to a later
time.
auto merge of #18253 : steveklabnik/rust/small_doc_fixes, r=huonw

All these stars aren't needed anymore.
Fail immediately if linking returns status code != 0
auto merge of #17683 : gereeter/rust/ident-to-name, r=pcwalton

This does a large chunk of #6993. It is based on top of #17654.
Update .mailmap
s/vtable2/vtable
auto merge of #17960 : mahkoh/rust/clone_from_slice, r=pcwalton

Old vs. New vs. Vec::push_all

```
test slice     ... bench:   3091942 ns/iter (+/- 54460)
test slice_new ... bench:   1800065 ns/iter (+/- 69513)
test vec       ... bench:   1804805 ns/iter (+/- 75609)
```
Fix sigaction on OS X
Add a lint for not using field pattern shorthands

Closes #17792.
auto merge of #17896 : mahkoh/rust/intmax, r=alexcrichton

Closes #17075

I don't know if this is correct. The easiest way to find out is to run the following program on all targets but I can't do it myself.
```c
#include <stdint.h>
#include <stdio.h>

int main(void)
{
	if (sizeof(intmax_t) != 8) {
		puts("ERROR");
		return 1;
	}
}
```
Print stack overflow messages for Windows, Linux and OS X

Fixes #17562
Use type-safe wrapper for TypeFlags
auto merge of #17813 : P1start/rust/lint-field-shorthand, r=huonw

Closes #17792.
Improve shootout-reverse-complement
ignore-android
Changes a little the description of take in the guide

Closes #18218
regex: Fix control flow in the parser
regex: Escaped literals can end ranges