Fix prompt error highlight characters

When deciding what character to color red for errors, we were
using IsSymbol - that was a bit too restrictive so it was changed
to be any non-whitespace and non-alphanumeric characters.

Fixes #127

Author: lzybkr

PSReadLine/Render.cs

@@ -209,16 +209,22 @@ private void ReallyRender()
 
                 while (promptChar >= 0)
                 {
-                    if (char.IsSymbol((char)_consoleBuffer[promptChar].UnicodeChar))
+                    var c = (char)_consoleBuffer[promptChar].UnicodeChar;
+                    if (char.IsWhiteSpace(c))
+                    {
+                        promptChar -= 1;
+                        continue;
+                    }
+
+                    if (!char.IsLetterOrDigit(c))
                     {
                         ConsoleColor prevColor = _consoleBuffer[promptChar].ForegroundColor;
                         _consoleBuffer[promptChar].ForegroundColor = ConsoleColor.Red;
                         WriteBufferLines(_consoleBuffer, ref _initialY);
                         rendered = true;
                         _consoleBuffer[promptChar].ForegroundColor = prevColor;
-                        break;
                     }
-                    promptChar -= 1;
+                    break;
                 }
             }
 

TestPSReadLine/Program.cs

@@ -119,8 +119,7 @@ static void Main()
             PSConsoleReadLine.SetKeyHandler(new[] {"Ctrl+D,Ctrl+X"}, CauseCrash, "", "");
             while (true)
             {
-                //Console.Write("C:\\Windows\nPS> ");
-                Console.Write("PS> ");
+                Console.Write("PS# ");
 
                 var line = PSConsoleReadLine.ReadLine();
                 Console.WriteLine(line);