Mediaplayer: Cleanup _format_time

- Rename variables and parameter for readablity
- Expand single line if
Mediaplayer: Cleanup parse_time

- Rename variables for readabilty
- Reordered if to reduce nesting
Mediaplayer: Cleanup parse_html

- Rename variables for readablity
- Inline single use variables
Mediaplayer: Cleanup parse_xml

- Few trailing spaces
- Rename variables for readablity
- Inline varaible declaration since it occurs directly after
initialization
Mediaplayer: Cleanup _load_captions

- Rename "c" to "$caption"
Mediaplayer: Cleanup _update_captions

- Rename variables for readability
- Skip jq object creation in the append()