Many errors in Greek tests

Start in tests/languages.rs and tests\Languages\el.rs, where the Greek tests are enabled and listed failures are defined. Run the Greek test set and compare the failing ClearSpeak and SimpleSpeak cases with their expected results. Done means the listed Greek tests run without errors, including the cases in the newly added test files.

@theodora-anto: Someone pointed out that the Greek tests weren't being run. I added the line in tests/languages.rs to turn them on and then saw all the tests in tests\Languages\el.rs were commented out. I uncommented them and there were lots of failures. Many were in new test files you added. But even ignoring them, there are still plenty of errors.

Were you aware of these?

    Languages::el::ClearSpeak::functions::explicit_times_more_implied_times
    Languages::el::ClearSpeak::functions::explicit_times_with_parens
    Languages::el::ClearSpeak::functions::more_implied_times
    Languages::el::ClearSpeak::functions::no_parens_number
    Languages::el::ClearSpeak::functions::times_following_paren
    Languages::el::ClearSpeak::functions::times_preceding_paren
    Languages::el::ClearSpeak::functions::times_sqrt
    Languages::el::ClearSpeak::mfrac::binomial
    Languages::el::ClearSpeak::mroot::msqrt_simple_pos_end_with_neg_root_2
    Languages::el::ClearSpeak::mroot::no_double_the_532
    Languages::el::ClearSpeak::msup::decimal_power
    Languages::el::ClearSpeak::sets::element_under_sum
    Languages::el::ClearSpeak::sets::element_under_sum_belongs
    Languages::el::ClearSpeak::sets::element_under_sum_element
    Languages::el::ClearSpeak::sets::element_under_sum_in
    Languages::el::ClearSpeak::sets::element_under_sum_member
    Languages::el::SimpleSpeak::functions::explicit_times_with_parens
    Languages::el::SimpleSpeak::functions::no_parens_number
    Languages::el::SimpleSpeak::functions::no_times_sqrt
    Languages::el::SimpleSpeak::functions::times_following_paren
    Languages::el::SimpleSpeak::functions::times_preceding_paren
    Languages::el::SimpleSpeak::linear_algebra::norm_subscripted
    Languages::el::SimpleSpeak::linear_algebra::not_gradient
    Languages::el::SimpleSpeak::mfrac::binomial
    Languages::el::SimpleSpeak::mfrac::binomial_non_simple_bottom
    Languages::el::SimpleSpeak::mfrac::binomial_non_simple_top
    Languages::el::SimpleSpeak::mfrac::binomial_non_simple_top_and_bottom
    Languages::el::SimpleSpeak::msup::decimal_power
    Languages::el::SimpleSpeak::sets::element_under_sum
    Languages::el::SimpleSpeak::subscripts::msub_not_simple
    Languages::el::SimpleSpeak::subscripts::msubsup_not_simple