Adds suggestion to use "screen" to README_CREST.txt for Vim 5.7 benchmark.
Adds suggestion to use "screen" to README_CREST.txt for Vim 5.7 benchmark.

jburnim/crest,wy7980/crest,wy7980/crest,wy7980/crest,jburnim/crest,jburnim/crest,jburnim/crest,wy7980/crest