fixes #1013
fix .gitignore for android studio files
Merge pull request #1014 from TShapinsky/issue_1013_null_drone

Fixes #1013 NullPointerException
Merge pull request #1016 from squilter/fix_.gitignore

fix .gitignore for android studio files
fix an issue causing the drone graphic to lose its connection state (color) on system events (screen rotation)..
Merge pull request #1018 from ne0fhyk/fix_graphic_drone_connection_state

Fix drone graphic connection state