[tin 2.1.0] snaphsots

[Urs Janßen]

I've made snapshots of the upcomming tin 2.1.0 (unstable) release.
New stuff:

- support for huge article numbers (2^63-1) if configured with
--enable-long-article-numbers and system has int_least64_t or
long long or quad_t. It's not enabled by default as article numbers
higher than 2^63-1 do violate the current NNTP RFC.

- with getart_limit set use LISTGROUP range instead of plain
LISTGROUP, if LISTGROUP range is not supported use only GROUP
(reduces traffic)

- with getart_limit set don't malloc base[]/arts[] for articles
below first_unread and outside the range. (reduces memory usage).

Even with --enable-long-article-numbers tin still can't handle more
than INT_MAX articles per group (i.e. 2^31-1). But as such groups
would require several GB of RAM just for the meta-data this isn't a
real problem (there is at least one provider with such a group:
alt.binaries.boneless 5896156915 1527513710 y) and starting
with this snapshot the group can be read with -G limit.

<ftp://ftp.tin.org/pub/news/clients/tin/unstable/snapshots/>

urs