v0.6.1

Fixed

• A panic "Unsupported uniform datatype! 0x1405" has been resolved that occurred
  on some devices where push constants were being emulated and only signed
  integers were supported.
• #66: A rounding error has been fixed when calculating the text width
  would cause the line width to be rounded down in some cases.
• If wgpu reports a SurfaceError::Lost, the create_surface() call is now
  correctly made on the main thread rather than the window thread. Thanks to
  @Plecra for reviewing the unsafe code and noticing this issue. This
  review also led to further reductions in the amount of unsafe code and
  improved the safety comments.