flesh out the source file descriptions for doxygen

src/common/aes.c

src/common/compat.c

src/common/container.c

src/common/crypto.c

src/common/crypto.h

src/common/log.c

src/common/log.h

src/common/test.h

src/common/torgzip.c

src/common/tortls.c

src/common/util.c

src/or/buffers.c

src/or/circuituse.c

src/or/command.c

src/or/config.c

src/or/control.c

src/or/cpuworker.c

src/or/directory.c

src/or/dirserv.c

src/or/dns.c