Mediaplayer: Cleanup keystroke handling

- Change to if/else if since only one keystroke can be handled per event
with the combinations tested
- Rename "e" to "event" for readablity
- Rename "v" to "volume" for readablity
- Inline some unnessisary ternary returns
- inline "$(this)" calls so they old get called when needed
Mediaplayer: Cleanup _get_loading_ind vars

Updating variable and parameter naming for readability
Mediaplayer: Cleanup _get_ui

- Cache dictionary lookups
- Inline timeline jquery object and remove object conversion
- Combine append() calls
Mediaplayer: Cleanup _intf

- Remove unnecessary typeof wrapping
- Expand single line ifs to multiline
- Added readable variable names for parameters
Mediaplayer: Cleanup _format_time

- Rename variables and parameter for readablity
- Expand single line if