Swift: Models and tests for numeric conversions

[geoffw0]

Add models and tests for (mostly) numeric conversions.

Fixed a flow issue with OptionalSomePattern I bumped into on the way.

TODO:

• can we catch this one as well:

	sink(arg: [UInt8](sourceString().utf8)) // $ MISSING: tainted=

• DCA run

[geoffw0]

DCA LGTM. I will fix the merge conflicts after this has had an initial review.

[d10c]

LGTM

[geoffw0]

Fixed merge conflicts. Changes after the merge need a quick review.

There were a number of changes to various test results as a result of the merge. One was a good change, the other two were undesirable. I've addressed them by adding proper barriers for Numeric values (in particular Int) in five injection-like queries. Previously we were depending on data flow not actually working through the constructs that were involved.

[geoffw0]

... I should probably add a second change note for the barriers ...

[geoffw0]

Second change note added (with no mention of the command injection query as it's still in experimental).

And added the numeric barrier to the regular expression injection query as well.

[d10c]

Looks good