expression view improvements

[yubowenok]

A few TODO tunings

• By default not show TFA
• Profile/TFA vertical axis ticks are a bit cluttered. Consider adjusting number of ticks based on the plot height.
• Zooming in could result in disappearing profiles. This is a bit confusing. I understand that you are restricting profiled genes to exist in the matrix. However I think since disappearing profiles are weird, it would be better to make them independent, so that profiled genes are kept intact when matrix row selection changes.
• If the user tries to add rows/columns that do not exist, it should show "no genes/conditions found" rather than "invalid input gene/condition selection".