call getpwuid, getgrgid and getpwuid only if NOT on Windows
gitignore generated files
use the standard Cwd module instead of PWD as a step to work on Windows as well
gitignore generated META files
asyncd: ident help options
asyncd: adding support for non std default rate

Adding an option for a very simple overriding the default update_rate value.
This enables a very easy 1 min polling setup.
plugins: start implementing a new framework for plugins writing.

Munin::Plugin::Framework allows a much easier way to write new plugins
by abstracting the underlying protocol between node and master.

The idea is to have the plugins only declare what they want to have
displayed, eventually merging the code for configuration and
value-setting, and leaving it to the framework to generate the
configuration and fetch output.
procsys: implement a new plugin to replace entropy, open_files and open_inodes.

This new plugin uses the new Framework to create graphs for all the
sysctl-related data as a signle round-trip.

There is only one change compared to the previous plugins: open_inodes
produces a more meaningful graph of allocated and free inodes, rather
than the previous one that used a fake max value (as it was actually
the kernel's allocation).

Both open_files and open_inodes graphs now use areastacks instead of lines.
plugins: rewrite new multigraph plugins for using the Framework
procfs: merge load and uptime plugins.

The new plugin with the new Framework code makes it cleaner to just
have one place where most of the /proc files are read.
snmp__if_multi: get the interface alias from SNMPv2 if it is defined
plugins/http_loadtime: add specific user-agent

I spent a bit of time looking what was calling http://127.0.0.1/ on
my server with the default wget user agent string.

Looked around a bit more and realized it was the Munin HTTP load
time plugin. Adding this simple user agent string so sys-admins
will know what it is when they look at their logs.
Add doc for missing node directives in munin.conf
Set "the munin project and its contributors" as authors, and use that in the copyright string.
Add node definitions to the munin.conf reference
master: update test for config default

Commit 1aec747c10f0d5077842294ca351b918b77fb1e9 added a
default for graph_strategy. test has be updated.
node: use a 5% tolerance for timings tests

If the tests are done on a VM, the timings are not precise enough. So increase the error margin to cope with it.

It was at 0.5%, and this commits sets it at 5%
Merge branch 'async-enh' into devel

Conflicts:
	node/_bin/munin-asyncd.in
doc: adding some context to async
master: add feature to disable graph_total

According to Philipp Niemann on the mailing-list :

    This is a new configuration option for munin.conf to deactivate the graphing
    of total values on a per-plugin scope.

    So currently one has to change the plugin itself, which is clumsy and only
    lasts till the next update of plugins.

Once set in the plugin code, no value can deactivate it.  This makes the
special value "undef" deactivate it. It can therefore be overriden properly
via munin.conf.

Closes: #827