Introduce log package

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log.Logger: add initial Logger type

timestamping still missing

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log.LoggerMap: singleton for Loggers, by Tag.

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log.Logger: made tag private

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log: fix LogLevel enum

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log:Logger: fix varadic usage in shutcut functions

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log: Logger: use public BaseEncoder() and StderrLogWrite() helpers

Signed-off-by: Alejandro Mery <amery@geeks.cl>
log: add toplevel Error() shortcut

Signed-off-by: Alejandro Mery <amery@geeks.cl>
net.Listen: no need to rename the standard `net` for in-module usage

Signed-off-by: Alejandro Mery <amery@geeks.cl>