Add support for switch with case statement instead of block statement #398

Job	Run time
catch-bad-whitespace	3s
bootstrap-pnut-sh (bash)	1m 26s
bootstrap-pnut-exe (bash, i386_linux)	4m 8s
bootstrap-pnut-sh (dash)	1m 53s
bootstrap-pnut-sh-with-pnut-exe (i386_linux)	11s
bootstrap-pnut-exe (bash, x86_64_linux)	4m 9s
bootstrap-pnut-sh (ksh)	48s
bootstrap-pnut-sh-with-pnut-exe (x86_64_linux)	12s
bootstrap-pnut-exe (bash, x86_64_mac)	4m 17s
bootstrap-pnut-sh (mksh)	18m 7s
bootstrap-pnut-sh-with-pnut-exe (x86_64_mac)	20s
bootstrap-pnut-exe (dash, i386_linux)	9m 35s
bootstrap-pnut-sh (yash)	1m 51s
build-without-warnings	28s
bootstrap-pnut-exe (dash, x86_64_linux)	11m 25s
bootstrap-pnut-sh (zsh)	13m 47s
bootstrap-pnut-exe (dash, x86_64_mac)	10m 4s
tests-exe (i386_linux, ubuntu-latest)	20s
bootstrap-pnut-exe (ksh, i386_linux)	1m 57s
tests-shell (bash)	21s
tests-exe (x86_64_linux, ubuntu-latest)	11s
bootstrap-pnut-exe (ksh, x86_64_linux)	1m 57s
tests-shell (dash)	17s
tests-exe (x86_64_mac, macos-latest)	17s
bootstrap-pnut-exe (ksh, x86_64_mac)	1m 18s
tests-shell (ksh)	27s
tests-shell (mksh)	2m 0s
bootstrap-bash-2_05a	31m 15s
tests-shell (yash)	1m 33s
compile-in-safe-mode	13s
tests-shell (zsh)	29s
pnut-variants-run (reader)	22s
pnut-variants-run (tokenizer)	1m 12s
pnut-variants-run (parser)	46s
success-message	1s
	2h 7m 40s

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