Added templates token

Support for env variable:
PLAYLIST - if set to 'yes' or 'true' files will be stored in subfolders named after playlist name or 'NA' if the files is not part of a playlist

Added variables:
RATE - to set a custom max download rate
MIN_SLEEP - to set a minim number of seconds to wait before next transfer (for playlist download)
MAX_SLEEP - to set a maximum number of seconds to wait before next transfer (for playlist download) 
RM_CACHE_DIR - in case of download problems, you may want to clear cache before each download, set to true or yes

Fix random mkv or mp4 format when specifying resolution

For the following sample list of formats, before this fix, given
`resolution=720`, it will select format code 247 instead of 136 because 247 is
after 136 and resulting in the `mkv` file container format instead of `mp4`.

`mp4` format is preferred for a wider compatibility with older devices.

This fix is inline with the existing `(url[2] == "best")` case that also prefer
`mp4` format.

```
format code  extension  resolution note
249          webm       audio only tiny   48k , webm_dash container, opus @ 48k (48000Hz), 8.49MiB
250          webm       audio only tiny   61k , webm_dash container, opus @ 61k (48000Hz), 10.87MiB
251          webm       audio only tiny  118k , webm_dash container, opus @118k (48000Hz), 20.99MiB
140          m4a        audio only tiny  129k , m4a_dash container, mp4a.40.2@129k (44100Hz), 22.91MiB
160          mp4        256x144    144p   47k , mp4_dash container, avc1.4d400c@  47k, 30fps, video only, 8.38MiB
278          webm       256x144    144p   73k , webm_dash container, vp9@  73k, 30fps, video only, 12.94MiB
133          mp4        426x240    240p   90k , mp4_dash container, avc1.4d4015@  90k, 30fps, video only, 15.96MiB
242          webm       426x240    240p  123k , webm_dash container, vp9@ 123k, 30fps, video only, 21.91MiB
134          mp4        640x360    360p  154k , mp4_dash container, avc1.4d401e@ 154k, 30fps, video only, 27.25MiB
243          webm       640x360    360p  233k , webm_dash container, vp9@ 233k, 30fps, video only, 41.23MiB
135          mp4        854x480    480p  247k , mp4_dash container, avc1.4d401f@ 247k, 30fps, video only, 43.70MiB
244          webm       854x480    480p  362k , webm_dash container, vp9@ 362k, 30fps, video only, 64.12MiB
136          mp4        1280x720   720p  408k , mp4_dash container, avc1.4d401f@ 408k, 30fps, video only, 72.24MiB
247          webm       1280x720   720p  602k , webm_dash container, vp9@ 602k, 30fps, video only, 106.56MiB
248          webm       1920x1080  1080p 1083k , webm_dash container, vp9@1083k, 30fps, video only, 191.63MiB
137          mp4        1920x1080  1080p 1128k , mp4_dash container, avc1.640028@1128k, 30fps, video only, 199.59MiB
18           mp4        640x360    360p  420k , avc1.42001E, 30fps, mp4a.40.2 (44100Hz), 74.34MiB
22           mp4        1280x720   720p 1302k , avc1.64001F, 30fps, mp4a.40.2 (44100Hz) (best)
```

add proxy support

add proxy support

add docker optinal variable to support youtube-dl proxy

add proxy support

Added audio-mp3 option

Added audio-mp3 option

and renamed previous audio option to include m4a

[Patch] Audio only option for web-ui and REST call. Change username field type for compatiblity

Change username field type for compatiblity

Audio only option for web-ui and REST call

The input field for username now has type=username, which will improve compatibility with password managers (KeepassXC for example).

update readme

Modifying so this will work behind HTTPS as well

downfloder -> downfolder

I'm replacing the 'http' in the protocol with 'ws'. If the protocol is just 'http' it will use 'ws' if it's 'https' it will end up being 'wss' (websocket secure)