Etcher

What's new in this version:

Improvements:
Add a basic command palette (experimental):
- Open the command palette with Ctrl+P (or Cmd+P on macOS)
- The list of commands is then shown and allows you to quickly launch actions, like launching a preview, open a project, etc...
- This is the first part of one of the Google Summer of Code 2020 project! A few commands are available now, but many more will be added in the next weeks to navigate through the project and edit any part of it in a few keystrokes.

Add more conditions/expressions to the Platformer Objects:
- Add the speed, jump speed and fall speed
- Add condition to check if platforms can be grabbed
- Add condition to check if the object can jump

- Added "Board walk with raycast" example
- Add an option to clear the shape painted using Shape Painter between each frame
- Add an action to pause the game during a preview: this is useful to then inspect the game with the Debugger
- Prevent a behavior to be selected in a function parameter if it's incompatible with the object
- Add buttons at bottom of events to add new events.
- Avoid showing a drop marker when an event can't be dropped in another (comment, etc...)
- Slightly improve startup speed

Add a border around conditions in the default theme:
- This avoids confusion about two events that are next to each others, in particular for new users
- Also normalize styling in other themes

Bug fixes:
- Fix memory leak leading to a crash in the editor when having a BB Text in the scene: also fix similar smaller memory leak when using other features
- Fix parameter popover in the events sheet shown behind editor panel title bars
- Fix instance variable not saved after a change if another instance is clicked while editing it
- Fix physics engine not applying change in size when using circle shape
- Fix scaffolding line colors between events and some colors in Nord theme
- Fix potential crash by adding a check to ensure built-in extensions are not overriden
- Fix internal warning (divider component in select list)