Add initial support for print

[leonardt]

Only works on top level ports

Supports an optional argument format_str which allows you to customize how the value is printed (by default it is %x).

Example usage:

    tester.print(circ.O, "%08x")

Adds tests for Actions, Tester, and the magma/verilator targets.

[coveralls]

Pull Request Test Coverage Report for Build 224

• 28 of 29 (96.55%) changed or added relevant lines in 5 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.9%) to 81.023%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fault/actions.py	12	13	92.31%

Totals
Change from base Build 211:	0.9%
Covered Lines:	491
Relevant Lines:	606

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💛 - Coveralls

[rsetaluri]

Wondering if we can rename this to like Print(format_str, *args) where we have some special syntax for a port (like %v or something else that's not used). The target functionality is the same, it just makes it more clear that this is just a print statement, not returning you the value inline as a peek normally would.

I.e. val = peek(foo.O) doesn't make sense here, though that's the normal usage of peek. Then if we have a non-compiled tester in the future that's running in real time, we can actually have a peek that returns a value.

[leonardt]

Okay that makes sense.

[leonardt]

If you're referring to the tester method peek, just caught that (sorry was find/replacing Peek, didn't catch the lower case)

[rsetaluri]

oh just saw you did that 😄