Use macros and strings to name testcases instead of variable names

[fjarri]

It seems that the mechanism of naming testcases based on variable names is not very convenient in many cases, after all. Perhaps we should restore the optional name parameter of the testcase, and create a macro like

@testcase "Some testcase description" (fixture1 => x, fixture2 => y) begin
    @test x == y
end

that would translate to

_generated_symbol = testcase(fixture1, fixture2; name="Some testcase description") do x, y
    @test x == y
end

[fjarri]

Seems that everything is done, closing.