Rewrite getPatchIndexBuffer

Closes #15

See merge request !6

Resolve "findRegular ist langsam"

Closes #9

See merge request !8

Resolve "Baue neighbors map auf der GPU"

Closes #16

See merge request !7

These models are not closed, they have at least one edge that is not
connected to another edge.

buddha, bunny and dragon were not tested as they have a lot of
triangles.

Resolve "Nachbarn sollten nur einmal berechnet werden"

Closes #13

See merge request !5

Remove use of glBindBufferRange

Fixes #10

Didn't work with some models. I'm guessing that there are requirements
for the offset (divisible by some power of 2 or something) that we just
happen to meet with some models but not with others.

New version binds the full output buffer but adds another buffer that
contains the offset into the output buffer.

See merge request !3

Fixes #10

Didn't work with some models. I'm guessing that there are requirements
for the offset (divisible by some power of 2 or something) that we just
happen to meet with some models but not with others.

New version binds the full output buffer but adds another buffer that
contains the offset into the output buffer.

Fixes #8