added new way to get media tokens

updated dependencies
improved popup
fixed downloading files in mobile firefox

added some success messages

fixed PDF files without file extension
updated README.md
updated dependencies

improved loading midi over midi button

Merge pull request #13 from ingui-n/dependabot/npm_and_yarn/es5-ext-0…

….10.64

Bump es5-ext from 0.10.62 to 0.10.64

added stop button to download audio and midi

removed storage from permissions

Merge branch 'master' of github.com:ingui-n/musescore-downloader

0.5.0 - resolves #3 && resolves #4

Added installation guide to README.md