Footer Sizing Issue with Footer Items

[mrhaubrich]

Is your feature request related to a problem? Please describe.
I've found the library and it is awesome, but when I added footerItems, the footerSeparator was in a bad position, in the middle of the sidebar, instead of the bottom, as expected.

Describe the solution you'd like
I've created a fork and added a enum "FooterFitType" that can be "fit" or "expand". And send it as a parameter to the SidebarX class, setting the default value as "expanded" so the new update won't break existing projects.

Describe alternatives you've considered
I've considered setting as default to always fit the items, instead of expanding, but maybe someone needs the expanded approach. Later, I've considered using a boolean to tell if it fits or not, but found more readable being a enum.

Additional context
Current approach:
Code:

Sidebar:

My solution:
Code:

Sidebar: