algo: Make a dict from an flat list

This is in preparation to take deeper dict constructs from the command
line. You can feed the optionslist directly constructed of type
"identkeyval" to it and it returns a fully deflated dict.

This is mainly needed for the resource model changes where we have to
modify the disk_state which is a 3 level dict:

disk_type/name:disk_reserved=10g

Signed-off-by: René Nussbaumer <rn@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>