SolarFan/Envelope changed based on user testing

Hey guys, I have updated the SE SF with the following:
1 New icons.
2. Changed the inputs conditionals so they behave the same way as the rest of the LB components. Components don't turn orange when they're dropped on to the canvas anymore.
3. Modified the SolarFan boolean union method, to deal with complex input geometries in a more user-friendly way. 
4. Added the 4 dates options for selecting the month range. 

Feedback is welcome.