- fixes error when running castopod on php<7.4

fixes #23

- add .editorconfig file
- format all files to comply with castopod's coding style
- switch parsedown dependency with commonmark library to better follow commonmark spec for markdown
- add prettier command to format all project files at once

closes #16

- add basic rollup config to bundle minified and browser compatible js
- use babel to transpile
typescript files to js
- add static code checkers: eslint and stylelint
- update package.json
scripts
- update DEPENDENCIES.md file to include rollup and popper
- set html in rss feed
description fields
- update Podcast and Episode entities to add description_html attribute
generated by parsing markdown to html using parsedown

#9

- bundle js using parcel
- add markdown editor, html editor, dropdown and tooltip features using third-party packages
- integrate optimized inline svg icons from RemixIcon using svgo and a php helper
- add scripts in package.json to bundle icons, images, css and js
- update tailwind config to add purgecss lookups and typography plugin
- refactor views to add missing pages in user journey
- update admin's holy grail layout using css grid

- add $mediaRoot parameter in app config
- add and refactor helpers : id3, media and url
- add basic vscode settings for code formatting in devcontainer.json
- set post_max_size to Dockerfile

- add james-heinrich/getid3 library as a dependency to composer.json
- update DEPENDENCIES.md file
- fix episodes table migration script
- add js devDependencies: prettier, @prettier/plugin-php and lint-staged to automatically format staged files before commit
- reformat all files to the prettier format
- refactor code by separating some logic as helper functions
- overwrite existing files when uploading new files with the same name

fixes #1

- add node service in docker-compose.yml
- update .devcontainer Dockerfile by adding node, npm and vim
- init package.json for npm with tailwindcss, postcss, commitlint and commitizen as dev dependencies
- update default layout main header and footer
- replace CI's welcome_message.php with home.php listing all podcasts
- add AUTHORS.md file
- add docs folder in which to place castopod's technical documentation