Add PICT line and basic font opcode support

[lubert]

Summary

• Adds basic text rendering support to QuickDrawEngine
• Fixes for some issues with PICT decoding

Fixes

• Fixed incorrect handling in SetOrigin, was treating dh/dv as absolute positions instead of deltas
• Changed FillRect/FillOval colors to use foreground/background colors from port state instead of hardcoded values.
• Changed PICT to draw on transparent so blending works

New opcodes

• Implemented LongText (0x0028), DHText (0x0029), DVText (0x002A), DHDVText (0x002B)
• Implemented Line (0x0020), LineFrom (0x0021), ShortLine (0x0022), ShortLineFrom (0x0023)

API Changes

• Added QuickDrawEngine::set_font_handler() to register callback for font loading

Samples

Reference exports from ResEdit:

Using QuickDrawEngine: