facelift the dialogs

[dk]

• use system dialog for ps/eps/pdf
• facelift the propertes dialog
• add color selectors for the graph in the properties dialog

[coveralls]

Pull Request Test Coverage Report for Build 4008370680

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 151 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.2%) to 35.204%

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Files with Coverage Reduction	New Missed Lines	%
/home/runner/work/PDL-Graphics-Prima/PDL-Graphics-Prima/blib/lib/PDL/Graphics/Prima.pm	151	35.93%
<!--	Total:	151		-->

Totals
Change from base Build 4008363930:	-0.2%
Covered Lines:	853
Relevant Lines:	2423

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💛 - Coveralls

[run4flat]

This looks good to me!

[mohawk2]

I have rebased this past your other change which I just merged, also a test fix that a recent change required (t/120* was leaving two files in the top directory).