(svn r1894) - Codechange: cleaned up the console a bit, wholly unified handling of text with that of editboxes

- Codechange: Introduction of Textbuf struct which not only holds physical data as length but also pixel-constrains (width) and information about the caret
- Codechange: Move Clipboard function to OS specific file. Currently only Windows has clipboard actions
- Feature: Editboxes, console and exit screen also accept the numeric-enter as a yes
- Feature: Navigation through text with cursor keys is possible, as well as arbitrary insertion (also paste) and deletion; both backspace and del keys. Functions DeleteTextBufferChar, InsertTextBufferChar and InsertTextBufferClipboard handle input and deletion. Navigation is done through MoveTextBufferPos.
- Fix: OTTD crash when opening 'add server' editbox
- CodeChange: fix up some stringwidth calculations in gfx.c. You can get the width in pixels of a character by calling GetCharacterWidth().

news_gui.c

@@ -539,7 +539,7 @@ static void GetNewsString(NewsItem *ni, char *buffer, uint max)
 			d[0] = d[1] = d[2] = d[3] = ' ';
 			d += 4;
 		} else if ((byte)*s >= ' ' && ((byte)*s < 0x88 || (byte)*s >= 0x99)) {
-			len += _stringwidth_table[(byte)*s - 32];
+			len += GetCharacterWidth((byte)*s);
 			*d++ = *s;
 		}
 	}