and automatically seed from time on first use

coverity#1242393 Don't call rand
coverity#1242404 Don't call rand
coverity#1242410 Don't call rand and additionally allow 0xFF as a value
coverity#1242409 Don't call rand
coverity#1242399 Don't call rand
coverity#1242372 Don't call rand
coverity#1242377 Don't call rand
coverity#1242378 Don't call rand
coverity#1242379 Don't call rand
coverity#1242382 Don't call rand
coverity#1242383 Don't call rand
coverity#1242402 Don't call rand
coverity#1242397 Don't call rand
coverity#1242390 Don't call rand
coverity#1242389 Don't call rand
coverity#1242388 Don't call rand
coverity#1242386 Don't call rand
coverity#1242384 Don't call rand
coverity#1242394 Don't call rand

Change-Id: I241feab9cb370e091fd6ccaba2af941eb95bc7cf