v3.4: Formatting and performance improvements, and more!

IMPORTANT: BREAKING CHANGES:

1. You will need to update your file_name_format and caption_format values for captions to work correctly (see below and the readme for more information)
2. The caption_leading_zeros option has been removed (use the new formatting options for the same functionality)
3. The card editor has been removed

Updates in v3.4 include:

1. Implementation of the day.js library for date parsing and formatting. This will break any existing file_name_format and caption_format settings, however there are now many more options for formatting, such as days of the week, etc. See the readme for more details
2. As a consequence of the new date parsing, the caption_leading_zeros option has been removed. These options are now available as formatting codes (e.g. M for 1 digit month and MM for 2 digits).
3. Another consequence, you no longer need to specify any extraneous characters (e.g. camera name) in file_name_format. The library is capable of extracting just the dates from the file name.
4. Added caption_format option of "AGO" which uses the fromNow() function in day.js for formatting elapsed time (e.g. "2 hours ago")
5. Ensured caption_format option of " " (a space) will leave the captions blank
6. Added new folder_format parameter. When your videos are stored in subfolders by date (such as Synology Surveillance Station), you can use this along with maximum_files and reverse_sort for MUCH faster load times. I.e. it will look only in the current folder for the first maximum_files files and will stop when it has enough, rather than loading from ALL folders as it did previously.
7. Further tweaked loading of videos to be more streamlined which should result in more reliable loading of the card
8. New options for video_autoplay, video_loop, and random_sort (thanks @mvitale1989!)
9. New option for video_muted
10. New options for media sources: include_images and include_video
11. file_name_format, caption_format, and folder_format can be specified at the card level or entity level, with any specified entity level taking precedence.
12. The popup for images is now larger. Additionally, keypresses and swipes will scroll through the images when viewing the popup
13. Fixed the issue causing scrolling when setting focus on the page load (by registering the keypress globally at the document level)
14. Removed the card editor. It has been broken for a while anyway, and the extra effort to update was a hurdle preventing me from getting these changes out.