fixes #1170
fixes #1199
nightMode: Create separate night mode module
nightMode: Add night mode file to browsers
nightMode: Begin migrating from styleTweaks to nightMode
migrate: Migrate nightMode settings
nightMode: Rename useSubredditStyleInDarkMode

Description slightly altered as well to reflect the change.
nightMode: Improve description of lightSwitch
styleTweaks: Use === instead of ==
migrate: Add moveStorage function for moving RESStorage options
migrate: Add moveStorageWithFunction function
nightMode: Migrate RESmodules.styleTweaks.nightModeWhitelist
styleTweaks: Fix spacing
styleTweaks: Slightly adjust use of jQuery variable
styleTweaks: Replace `this` with modules['nightMode']
nightMode: Reorder options
nightMode: Rename lightSwitch to nightSwitch and update description
nightMode: Convert lightOrDark into a boolean nightModeOn
nightMode: Convert all lightSwitch references to nightSwitch
styleTweaks: Check if nightMode *module* is enabled