fmbtwindows: screenshot prefers fmbtpng over convert
fmbtwindows: screenshot prefers fmbtpng over convert

screenshot perf improvement 10 - 20 %

giantpinkwalrus/fMBT,mlq/fMBT,violep01/fMBT,giantpinkwalrus/fMBT,pombreda/fMBT,heivi/fMBT,yoonkiss/fMBT,violep01/fMBT,mlq/fMBT,01org/fMBT,yoonkiss/fMBT,rseymour/fMBT,pombreda/fMBT,yoonkiss/fMBT,01org/fMBT,01org/fMBT,mixu-/fMBT,heivi/fMBT,pombreda/fMBT,heivi/fMBT,rseymour/fMBT,giantpinkwalrus/fMBT,mixu-/fMBT,mixu-/fMBT,mlq/fMBT,heivi/fMBT,rseymour/fMBT,mixu-/fMBT,mlq/fMBT,01org/fMBT,mlq/fMBT,rseymour/fMBT,heivi/fMBT,acozzette/fMBT,heivi/fMBT,rseymour/fMBT,acozzette/fMBT,pombreda/fMBT,heivi/fMBT,rseymour/fMBT,acozzette/fMBT,mlq/fMBT,mixu-/fMBT,mlq/fMBT,violep01/fMBT,pombreda/fMBT,yoonkiss/fMBT,pombreda/fMBT,01org/fMBT,yoonkiss/fMBT,acozzette/fMBT,pombreda/fMBT,giantpinkwalrus/fMBT,acozzette/fMBT,rseymour/fMBT,violep01/fMBT,giantpinkwalrus/fMBT,violep01/fMBT