Fix parsing in locales that use a different decimal separator.

[AbdielKavash]

This is a correction to #58.

Number parsing in MathExpression.parseMathExpression() will now try to use a NumberFormat given by the TextFieldWidget using it; or the system default NumberFormat if none has been provided (or if called from outside a TextFieldWidget).

This means that numbers are now correctly parsed in locales that use a different thousands and decimal separators than , and .. Hopefully this should fix tests failing for @Dream-Master .

However current code still uses a mix of locale-aware formatting, and String.valueOf(). Also, since the raw text of the widget is exposed to the user, there is no way to guarantee that whoever is using the widget follows locale settings correctly.

Specifically for integer numbers, right now, this does not matter; as BaseTextFieldWidget hides thousands separators; and so most common number formats will appear identical. But if anybody wants a widget that can show non-integer decimal numbers, or to show thousands separators (the latter of which I would like to do), this could cause problems.

(And just for clarity, this problem is not caused by either this PR or the previous one; it was present in the code before too. It was only not apparent because people didn't try to input decimal numbers into the text field.)

I can see at least two possible solutions:

• Stick our head into the sand and mandate the US (or some other) locale on everybody. (I am not necessarily implying that this is unreasonable.)
• Create a new type of widget, NumericWidget, which would only expose the numeric value to the user, and manage all input/parsing/display on its own. Then switch over any code that previously used a TextWidget to input numbers to the new numeric widget.

[Dream-Master]

Now more processes passed onle one not pass

    org.opentest4j.AssertionFailedError: expected: <123456.0> but was: <123.456>
        at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:151)
        at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:132)
        at org.junit.jupiter.api.AssertEquals.failNotEqual(AssertEquals.java:197)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:70)
        at org.junit.jupiter.api.AssertEquals.assertEquals(AssertEquals.java:65)
        at org.junit.jupiter.api.Assertions.assertEquals(Assertions.java:886)
        at com.gtnewhorizons.modularui.api.math.MathExpressionTest.NumbersBasic_Test(MathExpressionTest.java:21)

[AbdielKavash]

The failing test case should now be fixed (issue was in the test, not in the code). Please let me know if anything else fails.

[Dream-Master]

will try later

[AbdielKavash]

This PR is deprecated, I have reworked the parser more thoroughly and in the process addressed these issues as well.

See #60.