Add an option to grid to skip time marks with empty labels

[eugene-korobko]

Is your feature request related to a problem? Please describe.

Creating yield curve chats usually supposes using tenor scale. We implement it with creating "fake" time points to add space between actual data points. The problem is that grid knows nothing about "fake" points, it treats them as real and draw lines on them, this is undesired and unexpected

Describe the solution you'd like

I'd like suggest simple solution: add an option for grid to skip tick marks with empty labels. This looks consistent and easy to implement