Unfortunately, easymesh code still relies heavily on its specifics, so I’m
letting it live as lol::easy_array for the near future. But it’s going away.

This is the first step to getting rid of lol::array in favour of std::vector.

We used to have lol::map::empty() to empty maps, but in std::map
this method is called clear(). It sounds safe to harmonise between
our types and have lol::array::clear() too.

We already have the convenient degrees() and radians() functions to convert
between angle formats. This commit involves a lot of refactoring here and
there and I may have missed some places where conversions were needed. But
hopefully there aren’t may such places.

The containers no longer force the user to use the ptrdiff_t type for
size information. For convenience, size() now always returns an int,
and the size_s() method offers a way to handle arrays with more than
2 billion elements. Internally, we still use ptrdiff_t, though.

Since so much code had to be changed, I took the opportunity to get
rid of capitalised accessors for classes that are lowercase.

First pass on EzMesh integration (doesn't work yet)

Big FAT pass on windows-warning. It is better now.