DB48X: HP48-like RPL implementation for DM42

[c3d]

Version 0.4.2 is out.

https://github.com/c3d/DB48X-on-DM42/rel...tag/v0.4.2

New features:

Display folder marker on directories in VariablesMenu (#309)
Alternate menu styles (sqare vs. rounded, single-line or 3-line) (#310)
line, circle, ellipse, rect and rrect graphic commands (#311, #316, #318)
linewidth, foreground, background graphic commands (#312)
ppar special variables for user coordinates (#319)
cllcd to clear the screen
drax to draw plotting axes (#321)
draw command to plot a function (#323)
wait command to wait for a delay or key press (#324)
Bugs:

Memory corruption when GC was triggered in a constructor (#325)
Improve complex_promotion to avoid undesirable complex format changes
Wrong pattern alignment in screen blitting operations
Off by one error in width and height of blitter rectangles (#
Conversion of fractions to uint32 (#321)
Conversion between bignum and uint32 / int32
Improvements:

Update dmcp commit to include a single fix for _exit
Better rendering of folder menus, looks more like a folder (#310)
Add .clang-format file to facilidate standard code formatting
Add AUTHORS file
Global variable lookup is now case-independent