snmp plugin: Improve some comments.
snmp plugin: Rename a couple of confusing variables.

"head" and "tail" are way better names, I hope.
snmp plugin: Expand tabs.
snmp plugin: Improve subtree matching.

Some MIBs use subtrees with an unusual OID naming schema. For example,
some network hardware encodes the MAC address in the last six parts of
the OID. Previously, the code only checked the last part of the OID
("sub-id") and assumed this was increasing. This assumption is not true
in such naming schemas and is not required by SNMP. This patch fixes
this behavior by comparing the entire "OID suffix".

This hopefully fixes Github issue #131.
Fixed bugs that prevented to "make distcheck"

Fixes Github issue #132.

Signed-off-by: Florian Forster <octo@collectd.org>
configure: Only set the Perl interpreter if the argument is a file.

This fixes Github issue #137.
snmp plugin: Fix iterating over tables without an instance configuration.

Also should fix incorrect handling of instance values; the first one would
be skipped.
The commit 3bda88e8b425f43644e303e6957e38ae59c1bc83 change the shell from sh to bash.
To fix the configure script generation error: remove the echo whith \c used in sh.

Note: bash is not installed in AIX by default.
Signed-off-by: Florian Forster <octo@collectd.org>
snmp plugin: Check the return value of csnmp_oid_suffix().

Also fix an issue where the complete OID is compared with only the suffix.

Thanks to Mark Juric to test the changes and point out these problems.

Issue: #131
snmp plugin: Fix incorrect comparison in csnmp_oid_compare().
src/utils_avltree.c: Fix an off-by-one error in c_avl_insert().

When inserting the first node in the tree, the size is not incremented.
This causes c_avl_size() to return one element too little.

Thanks to Yves Mettier for debugging this!
Merge branch 'ff/snmp' into collectd-4.10
Merge branch 'collectd-4.10' into collectd-5.0

Conflicts:
	src/snmp.c
Merge branch 'collectd-5.0' into collectd-5.1

Conflicts:
	src/snmp.c
Merge branch 'collectd-5.1'
Merge remote-tracking branch 'origin/collectd-5.1' into collectd-5.1
Merge branch 'collectd-5.1'
src/utils_format_graphite.[ch]: Add the "store_rates" option.

This functionality must have been lost in the refactoring that added
Graphite support to the AMQP plugin.
Merge remote-tracking branch 'octo/master' into cl/osx-gcrypt-1.50