Revert "leapDay" stuff. Update documentation #4642

Job	Run time
gcc	11m 19s
gcc (CFLAGS=-DTCL_NO_DEPRECATED=1)	11m 22s
gcc (--disable-shared)	11m 27s
gcc (--disable-zipfs)	11m 18s
gcc (--enable-symbols)	11m 42s
gcc (--enable-symbols=mem)	13m 12s
gcc (--enable-symbols=all)	14m 33s
msvc	10m 32s
msvc (CHECKS=nodep)	10m 29s
msvc (OPTS=static)	10m 37s
msvc (OPTS=noembed)	10m 31s
msvc (OPTS=symbols)	10m 36s
msvc (OPTS=symbols STATS=compdbg,memdbg)	14m 49s
	2h 32m 27s

Provide feedback