0.3.0

specify a starting wave shift is made possible;

0.2.4

add new tests;
dynamically change the wave cycles can work

Fix pause and unpause bug

Animation glitch happens when pausing and unpausing the waving animation;
This was mentioned in 0.2.1; fixed in 0.2.2;

add wave duration support

Pause and unpause waving animation has a noticeable time drift. The cause is still under investigation, so use it with caution.