fix issues with strandtest_nodelay()

[hathach]

issue is reported by user in https://forums.adafruit.com/viewtopic.php?t=209836

• fix slower swipe, 5s timeout before next to new pattern
• fix The wipes also do not start at the same pixel: pixelCurrent reset to 0 when move to new pattern
• fix theaterChase() incorrect behavior (with only 2 first pixel fast blinking)

there is more issues but it require a bit of reword since theaterChase() does not seems to be equivalent to the one in delay version of strandtest
TODO: draft PR, will mark as ready once fixed all the issues later.