Add support for rendering geometry range

[MortimerGoro]

No description provided.

[bluemarvin]

I don't want to nit pick (but I will 😅). I think I would prefer it be structure one of these two ways:

    if (m.rangeLength == 0) {
      VRB_GL_CHECK(glDrawElements(GL_TRIANGLES, maxLength, GL_UNSIGNED_SHORT, 0));
    } else if ((m.rangeStart + m.rangeLength) <= maxLength) {
      VRB_GL_CHECK(glDrawElements(GL_TRIANGLES, m.rangeLength, GL_UNSIGNED_SHORT, (void*)(m.rangeStart * sizeof(GLushort))));
    } else {
      VRB_WARN("Invalid geometry range (%u-%u). Max geometry length %d", m.rangeStart, m.rangeLength + m.rangeLength, maxLength);
    }

or

    if ((m.rangeStart + m.rangeLength) <= maxLength) {
      const uint32_t length = m.rangeLength ? m.rangeLength : maxLength;
      VRB_GL_CHECK(glDrawElements(GL_TRIANGLES, length, GL_UNSIGNED_SHORT, (void*)(m.rangeStart * sizeof(GLushort))));
    } else {
      VRB_WARN("Invalid geometry range (%u-%u). Max geometry length %d", m.rangeStart, m.rangeLength + m.rangeLength, maxLength);
    }

[MortimerGoro]

np, PR updated!