[FEATURE REQUEST] Check python syntax when saving edits to plugins

[gabriel-v]

Problem:

Syntax errors are not captured at save time, instead they happen at plugin execution time, at which point the error only shows up in the logs.

Feature description:

• check python syntax before accepting plugin edit / load / execution (calling ast.parse on the python text should be enough)
• display errors in a more obvious way (a dedicated error console with 10min of history would be nice)