Continued work on clocks and seeking support

Here’s a very raw preview of seeking support utilising speed changes. Rewind support isn’t completely implemented, but can be generally fixed with a few lines of change (though the correct solution will take a bit more thinking, as this was achieved by disabling some game-wide optimisations).

The end goal is to allow seeking in both directions with completely accurate scoring and playback. I actually already achieved this on lazer-transitional in a distant past and am using similar techniques to reimplement this on lazer, so it’s quite familiar (yet still daunting) territory!

Added support for lead-in time

Makes a lot of maps playable that previously weren’t. Haven’t extensively tested this yet, and it will likely receive further revisions over the next few days.

Other things

• Fix disabling mouse buttons causing auto to stop working #677.
• osu!taiko difficulty calculations are in! Note that this will only apply to newly imported beatmaps #675.
• osu!taiko drumroll conversion has received some minor fixes #663.
• ..as have swells (spinner converts) #676.
• My changes from yesterday have been merged (improving replay playback accuracy) #672 & #667.

New release available

2017.426.0 is now available from github releases (or via auto-update if you already have lazer installed)! Contains everything above.