improve clone_from_slice performance
add intmax
Part of #6993. Moved a bunch of uses of Ident to Name
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.
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)
```
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;
	}
}
```
Add a lint for not using field pattern shorthands

Closes #17792.
Update tests with the new error messages
Only include variable IDs in diagnostics when there's more than one

Diagnostics such as the following

```
mismatched types: expected `core::result::Result<uint,()>`, found `core::option::Option<<generic #1>>`
<anon>:6     let a: Result<uint, ()> = None;
                                       ^~~~
mismatched types: expected `&mut <generic #2>`, found `uint`
<anon>:7     f(42u);
               ^~~
```

tend to be fairly terse to new users. While specific type var IDs are valuable in
diagnostics that deal with more than one such variable, in practice many messages
only mention one. In those cases, leaving out the specific number makes the messages
slightly less terrifying.
Update tests with the new diagnostic tweaks