Port some of the forked features #79
Description
There are features in a number of forks that might make sense here as well. Just a pity that people don't offer them voluntarily in PRs 😭 😞
e.g. https://github.com/ouoam/nodemcu-pyflasher
- Disable Flash button when not select file
- Add support file drop
- Report error and info using Modal
- Show serial port description
- Make flash label animate when flashing (or similar)