feat(color): enhancements and fixes for Lua LVGL API.

[philmoz]

Fix some issues and add some new features to the Lua LVGL API.

New:

• line and triangle primitives
• message popup dialog
• expose buttons for for font, alignment, color, timer, switch and source pickers
• generic popup dialog that can be filled with other things
• lvgl.isAppMode() function to let widgets know when app mode is active
• additional containers for creating layouts (box and setting)
• flex layouts

Fixes:

• colors are updated when theme changes
• fix memory leaks when stand alone scripts close
• run stand alone scripts in a separate Lua state and use lua_pcallk() to prevent cross boundary errors (color only)

[philmoz]

Example of new features:

Dialog and popups for selecting font, source, etc:

Message dialog:

Line and triangle primitives: