Is your feature request related to a problem and/or adding functionality? Please describe.
Zepto is no longer maintained (last substantial commit was Aug 2017). Given this it seems to make sense to remove Zepto support in the next major release of IM.

A few other justifications:

1. ImageMapster v1.3.2 was just released and provides full support for Zepto so this allows us the opportunity for a "clean" break
2. Migrating IM to a Native JS library is on the roadmap so reliance on jQuery/Zepto will no longer be required. Even as a Native JS library, we can expose jQuery support but support for Zepto just does not seem worthwhile given the difference in the APIs, lack of UMD support, etc.
3. In a module scenario, module builders provide tree-shaking support reducing the original benefits of Zepto (smaller footprint given, at the time, jQuery's large footprint).

If anyone feels otherwise and/or has any thoughts, please discuss :)

Describe the solution you'd like
Remove Zepto support in v2.0.0

Describe alternatives you've considered
N/A

Additional context
N/A