Bandwidth improvements when retrieving summary ith IMAP

[Philip Van Hoof <spam pvanhoof be>]

This needs testing with as much IMAP servers as possible:

I removed two headers from the summary retrieval code. This will consume
less in two directions (upload and download) as both the query and the
answer included the header names, and the answer also included the
header answer.

The removed ones are MIME-VERSION and CONTENT-TYPE. I also improved
detecting how much and which UIDs you still need to fetch from the
server, and I improved parsing the result (I removed the need for a
GData, which should cause less memory consumption too, or at least less
allocations and deallocations happening).


ps. For testing you can use this to slowdown your connection:

tc qdisc del dev eth0 root
tc qdisc add dev eth0 root handle 1: netem delay 700ms
tc qdisc add dev eth0 parent 1: handle 10: htb default 1
tc class add dev eth0 parent 10: classid 10:1 htb rate 32kbit ceil 40kbit

tc qdisc del dev eth1 root
tc qdisc add dev eth1 root handle 1: netem delay 700ms
tc qdisc add dev eth1 parent 1: handle 10: htb default 1
tc class add dev eth1 parent 10: classid 10:1 htb rate 32kbit ceil 40kbit


-- 
Philip Van Hoof, software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://www.pvanhoof.be/blog