Feature: Immersive Jump Label Style and Word Jump

[zhaocai]

Immersive Jump Label Style

As discussed in issue #5, word-based jump generates too many labels. The result is interruptive due to the sudden emerging of numerous colorful labels. This pull request tunes the style to be relatively more immersive as demonstrated below.

smalls:start

Word Jump Implementation and Issues

smalls:word-jump

As shown in the above screenshot, two issues need to be dealt with.

1. The search highlight should be removed when jump starts.
2. The labels overlay on top of the search box.

In addition, the code to implement word jump is not optimal; it is likely need to be refined.