* allow setting and getting of pageview indicator opacity. fix some documentation comments
* don't draw the indicator the selected indicator is currently overlapping
* add a tweaked opacity to one of the test cases
* remove unused variable
* convert tabs to whitespace
* change constexpr to static const
* fix iterator invalidation when adding or removing pages from the pageview
* allow setting and getting of pageview indicator opacity. fix some documentation comments
* don't draw the indicator the selected indicator is currently overlapping
* add a tweaked opacity to one of the test cases
* remove unused variable
* convert tabs to whitespace
* change constexpr to static const
* Use range-based for-loops and allocate std::vector size(), end(), cend(), rend(), crend() on the stack where favorable.
Other minor trivial changes were applied.
* Fixed Android compilation error
* Fixed windows-universal compilation error