Write a nice new man page in AsciiDoc

Taking some preliminary steps for inclusion in Linux distributions.

The help message has been slightly improved and the README extended,
with part of it now residing in the man page.

One less GNU dependency, for what it's worth.

CMakeLists.txt

@@ -87,18 +87,20 @@ install (PROGRAMS json-format.pl DESTINATION ${CMAKE_INSTALL_BINDIR})
 install (FILES LICENSE DESTINATION ${CMAKE_INSTALL_DOCDIR})
 
 # Generate documentation from program help
-find_program (HELP2MAN_EXECUTABLE help2man)
-if (NOT HELP2MAN_EXECUTABLE)
-	message (FATAL_ERROR "help2man not found")
-endif (NOT HELP2MAN_EXECUTABLE)
+find_program (ASCIIDOCTOR_EXECUTABLE asciidoctor)
+if (NOT ASCIIDOCTOR_EXECUTABLE)
+	message (FATAL_ERROR "asciidoctor not found")
+endif (NOT ASCIIDOCTOR_EXECUTABLE)
 
 foreach (page ${PROJECT_NAME})
 	set (page_output "${PROJECT_BINARY_DIR}/${page}.1")
 	list (APPEND project_MAN_PAGES "${page_output}")
 	add_custom_command (OUTPUT ${page_output}
-		COMMAND ${HELP2MAN_EXECUTABLE} -N
-			"${PROJECT_BINARY_DIR}/${page}" -o ${page_output}
-		DEPENDS ${page}
+		COMMAND ${ASCIIDOCTOR_EXECUTABLE} -b manpage
+			-a release-version=${project_VERSION}
+			"${PROJECT_SOURCE_DIR}/${page}.adoc"
+			-o "${page_output}"
+		DEPENDS ${page}.adoc
 		COMMENT "Generating man page for ${page}" VERBATIM)
 endforeach (page)
 
@@ -111,7 +113,8 @@ foreach (page ${project_MAN_PAGES})
 endforeach (page)
 
 # CPack
-set (CPACK_PACKAGE_DESCRIPTION_SUMMARY "Shell for running JSON-RPC 2.0 queries")
+set (CPACK_PACKAGE_DESCRIPTION_SUMMARY
+	"A shell for running JSON-RPC 2.0 queries")
 set (CPACK_PACKAGE_VENDOR "Premysl Eric Janouch")
 set (CPACK_PACKAGE_CONTACT "Přemysl Eric Janouch <p@janouch.name>")
 set (CPACK_RESOURCE_FILE_LICENSE "${PROJECT_SOURCE_DIR}/LICENSE")