Timestamp edit

[leonardt]

Addresses issue where ncsim will not recompile a test bench if the new test bench file is generated within 1 second of the previous test bench file, see https://github.com/StanfordAHA/lassen/issues/111.

This forces fault to, by default, check whether the test bench exists, if so, diff the modification timestamp on the new file with the old file. if the new file is less than or equal (handling the case when this happens multiple times in a row), fault sets the new file to be "newer" than the old file.

[coveralls]

Pull Request Test Coverage Report for Build 1051

• 6 of 14 (42.86%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.3%) to 75.983%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
fault/system_verilog_target.py	6	14	42.86%
<!--	Total:	6	14	42.86%	-->

Totals
Change from base Build 1029:	-0.3%
Covered Lines:	1392
Relevant Lines:	1832

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💛 - Coveralls