Lots of changes and bugfixes

- Switched from browser.storage.sync to browser.storage.local to prevent MAX_WRITE_OPERATIONS_PER_HOUR error (this will "delete" your settings, sorry)
- Cleaned up translations, fixed incorrect behavior of some labels
- Transitioned to new websites data location ("ScheduleBlock_Websites"), since your data is unfortunately getting "deleted" anyway due to the first fix
- Added alert with reason when import of settings fails

- Moved default settings values to RecordStorage
- Completely reworked RecordStorage to hopefully make it thread safe
- Fixed timeout function not increasing duration on the last cycle
- Action when triggered is now more customizable (you can choose between redirection, closing of the window and execution of custom code)
- Created credits in the settings, listed image authors and licenses
- Made timeouts very customizable using similar format to time strings
- Reworked most of the project so that it works on Firefox (.sendMessage(), browser vs chrome, etc.)

- Fixed a critical bug that extension wouldn't work if specific key wasn't already present due to misplaced early return
- Fixed a smaller bug that details wouldn't be shown on deletion confirmation prompt

- Moved settings to popup, since the top bar was getting crowded
- Moved editing records to popup, since the main table was getting really crowded
- Added nice icons by Lorc (Cog) and Delapouite (Pencil), see section above for more details.
- Made ACL check frequency customizable in the options menu
- Added option for entering timeouts, implemented logic
- Restructured lot of the project into separate classes

- Shortened code for generating table by using more loops
- Added validation when changing times
- Added validation when importing settings
- Added simple framework for translating the extension, czech translation

- Added JSDoc signatures, improved code structure
- Options page background color can now be changed with a color picker
- Small design improvements (unified box sizes and margins)