From now on, it shouldn't complain about a missing module,
if in fact it is already fetched

Action variable from the top manifest is now passed
everywhere. It means, it is present when parsing all
manifests and it can be used for any purposes.

If a module has "fetchto" variable defined, then all
it's modules are fetched to this destination. If the
variable is indefined, then it is taken the parent.

Now modules to be fetched are recognized properly

If one the connection data is not given when the program is run
(--synth-server, --synth-user), hdlmake checks if the missing
variable is set in env variables (HDLMAKE_SERVER and HDLMAKE_USER
respectively)

A manifest variable 'syn_name' has been introduced
instead of 'name'. This variables indicates the remote
directory to be used. If it is not set in the manifest, its value
is based on the syn_project variable.