Fix Mesh Objects with missing textures or wrong texture path now import without texture
Cleanup: remove unused pointer in Heap
Cleanup: simplify heap popmin
Add edgehash remove, clear functions, Heap clear

Edgehash was missing removal functions (remove, popkey, clear),
since it wasn't needed so far, but is based on same code as ghash which has them.

also add heap clear() method so we can reuse heaps.

(needed for upcoming fix).
add beautify for polyfill
initial working code