Version: ?.?.?

Bug Description

There are 2 problems with multiple forms on one page:

1. if both forms have a field with the same name the input id's will be identical resulting in 2 html elements having the same ID
2. validating checkboxes with the same name is not possible

Please see this forum post for screenshots and a screencast:
https://forum.nette.org/en/30969-multiple-forms-on-one-page-standalone-version#p198618

Expected Behavior

all fields should have unique names