0.8.1

Improve GPU texture cache performance by partitioning the glyph lookup table by font & glyph id.

name                                                    control.stdout ns/iter  change.stdout ns/iter  diff ns/iter   diff %  speedup 
gpu_cache::cache_bench_tests::cache_bench_tolerance_1   3,004,912               2,502,683                  -502,229  -16.71%   x 1.20 
gpu_cache::cache_bench_tests::cache_bench_tolerance_p1  5,081,960               4,638,536                  -443,424   -8.73%   x 1.10