Support dimableIdentifierType-style names

[gkelly]

As of CMSIS-SVD 1.3.3 the schema allows for dimableIdentifierType
names in several places. This change uses the regular expressions from
the CMSIS-SVD 1.3.6 XSD for both dimableIdentifierType and
identifierType. While there is prose in ARM documentation suggesting
that all names must be valid ANSI C identifiers this is not born out by
the schema constraints.

---

This appears to have a net positive effect on the cargo test results:
Before: test result: FAILED. 253 passed; 381 failed; 0 ignored; 0 measured; 0 filtered out
After: test result: FAILED. 424 passed; 210 failed; 0 ignored; 0 measured; 0 filtered out

[burrbull]

https://docs.rs/once_cell/1.3.1/once_cell/sync/struct.Lazy.html

static PATTERN: Lazy<Regex> = Lazy::new(|| {
    Regex::new("^[_A-Za-z0-9]*$").unwrap()
});

[gkelly]

https://docs.rs/once_cell/1.3.1/once_cell/sync/struct.Lazy.html

static PATTERN: Lazy<Regex> = Lazy::new(|| {
    Regex::new("^[_A-Za-z0-9]*$").unwrap()
});

Done.

[gkelly]

Ran cargo fmt in latest push.

[gkelly]

I believe this is ready for review, but I'm unsure what the correct way to request reviewers on this repo is. Is there a queue I can put this in? Not trying to rush anyone, just want to make sure it doesn't fall through the cracks. :)

[burrbull]

bors try

[bors]

try

Build succeeded:

• continuous-integration/travis-ci/push

[burrbull]

bors r+

[bors]

Build succeeded:

• continuous-integration/travis-ci/push