All current renderers and muxers have no issues with longer timestamps.
However, classic VSFilter keeping track of time with a 32-bit int,
leads to a more meaningful limit at 596h, so enforce that instead.
Since the stringification code for SRT and ASS (but not SMPTE) relied on
hours being single digit, replace them with a simple format string.
GUI inputs are still limited to <10h, but at least
pre-existing timestamps no longer get mangled.
The highlighting distinguishes drawing commands from coordinates, and
colors x and y coordinates in different colors to make coordinates
easier to visually parse. Furthermore, in cubic Bezier curves, it
underlines the coordinates which corresponds to endpoints of the curves.
Use explicitly defaulted destructors for base cases when possible,
eliminate aggregate initialization constructors where possible, and push
some more stuff to NSDMIs.