Add support for Unicode legacy computing symbols block to LineBlockChararcters
This merge request adds drawing of more line and block characters (optionally) independent of the font used.
The characters are from the Symbols for Legacy Computing
range, defined here:
- 3x2 blocks drawing characters (code points 0x1fb00-0x1fb3b)
- Smooth mosaic terminal graphic characters (0x1fb3c-0x1fb6f)
- Block elements (0x1fb70-0x1fb8b)
Changed TerminalPainter::draw input from QChar to uint (for ucs4).