No, Mixcraft does not have a warp marker feature, but we've entertained the thought several times. We'll just have to see what Mixcraft 7 brings.
In current versions of Mixcraft, we have something we call FlexAudio. Hold down the Ctrl key and position the mouse cursor over the end of an audio clip until it turns into hands. You can then stretch or shrink the sound. Instant time-stretching!