'View.HotKey' automatic setting supports only char.IsLetterOrDigit

[tig]

	[Fact]
	public void Text_Change_Sets_HotKey ()
	{
		var view = new View () {
			HotKeySpecifier = new Rune ('_'),
			Text = "_Title!"
		};
		Assert.Equal (Key.T, view.HotKey);

		view.Text = "T_itle!";
		Assert.Equal (Key.I, view.HotKey);

		// BUGBUG: '!' should be supported. Line 968 of TextFormatter filters on char.IsLetterOrDigit 
		//view.Text = "Title_!";
		//Assert.Equal (Key.D1 | Key.ShiftMask, view.HotKey);
	}

I can see no reason for this limitation.

[tig]

Fixed in #2927

new code in TextFormatter.FindHotKey:

Updated unit tests:

[Theory]
//[InlineData ("_\"k before", false, Key.Null)] // BUGBUG: Not sure why this fails
[InlineData ("\"_k before", true, Key.K)]
[InlineData ("_`~!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?", true, (Key)'`')]
[InlineData ("`_~!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?", true, (Key)'~')]
//[InlineData ("`~!@#$%^&*()-__=+[{]}\\|;:'\",<.>/?", true, (Key)'_')] // BUGBUG: Not sure why this fails
[InlineData ("_ ~  s  gui.cs   master ↑10", true, (Key)'')] // ~IsLetterOrDigit + Unicode
[InlineData (" ~  s  gui.cs  _ master ↑10", true, (Key)'')] // ~IsLetterOrDigit + Unicode
[InlineData ("non-english: _кдать", true, (Key)'к')] // Lower case Cryllic K (к)
public void FindHotKey_Symbols_Returns_Symbol (string text, bool found, Key expected)
{
	var hotKeySpecifier = (Rune)'_';

	var result = TextFormatter.FindHotKey (text, hotKeySpecifier, false, out int _, out Key hotKey);
	Assert.Equal (found, result);
	Assert.Equal (expected, hotKey);
}

[Theory]
[InlineData ("\"k before")]
[InlineData ("ak second")]
[InlineData ("last k")]
[InlineData ("multiple k and r")]
[InlineData ("12345")]
[InlineData ("`~!@#$%^&*()-_=+[{]}\\|;:'\",<.>/?")] // punctuation
[InlineData (" ~  s  gui.cs   master ↑10")] // ~IsLetterOrDigit + Unicode
[InlineData ("non-english: кдать")] // Lower case Cryllic K (к)
public void FindHotKey_Legacy_FirstUpperCase_NotFound_Returns_False (string text)
{
	bool supportFirstUpperCase = true;

	var hotKeySpecifier = (Rune)0;

	var result = TextFormatter.FindHotKey (text, hotKeySpecifier, supportFirstUpperCase, out int hotPos, out Key hotKey);
	Assert.False (result);
	Assert.Equal (-1, hotPos);
	Assert.Equal (Key.Null, hotKey);
}