xivo-confd creates configs with these kind of labels, but xivo-provd
plugins expect the 'label' key to NOT be defined if the label is
unspecified, i.e. if a default label must be used.

This was a bit problematic on the D745, since when not specifying a
label, the phone was automatically creating a label from the
"fkey_value" value, and for BLF function keys, the generated label was
actually something like "1001|*8", which was quite ugly.

The plugin only supports the D745 currently and is a work in progress.

For xivo-yealink-v73 and xivo-yealink-v80 plugins only.

Deprecated in favor of xivo-cisco-sccp-9.4.

To use the latest one, which is the same as the one used by the
xivo-cisco-sccp-9.4 plugin.

For most models...

So that the documentation on the "minimum required version" of each
plugin is sane.

This is used by xivo-provd to prevent information leak from brute-force
attacks.

Deprecated in favor of xivo-polycom-5.4.3.

This is redundant with with the default config.

The 5.4.3 Polycom documentation says this is disabled by default, but
my tests show this is not the case.

Note that the VVX101 and VVX201 also have it disabled, even if they don't
support the remote XiVO directory.

They don't have a microbrowser (or XML browser, i.e. they can't access
the XiVO remote directory), so don't display a key that do nothing on
them.

So that the MAC address is also extracted when a request for
<mac>-user.cfg is done.

The 5.4 firmware is necessary to support the VVX101 and VVX201 phones.

The plugin is working, but there's still more tests to be done on the
phones, and some things seems a bit broken (the remote directory on the
VVX101 and VVX201, the "remote directory" softkey location, the default
configuration of the second line key on the VVX101).

Only available for some models, see http://projects.xivo.io/issues/6134
for more information.

For those models for which space is quite limited, i.e.:

* T19P E2
* T21P E2
* T23
* T40P

They share all the same language file it seems.

The EXP20 is an expansion module for the T27P and T29G. Like the EXP40,
you can program up to 40 function keys on it (20 functions keys per page
and 2 pages per extension module), but contrary to the EXP40, it does
not have physical keys to switch from one page to the other: you instead
have to manually configure a function key to do the page switching.
Here's an example configuration:

   expansion_module.1.key.1.type = 37
   expansion_module.1.key.1.label = PAGE 1

   expansion_module.1.key.21.type = 37
   expansion_module.1.key.21.label = PAGE 2

See http://projects.xivo.io/issues/6100#note-7 for more details.

Patch contributed by Julien Revert.

Use the same style as the xivo-yealink-v80 plugin, i.e. device not shown
in the description, and not particular markup in the firmware
description.

Do not show non-officially supported devices in description, e.g.:

* T23
* T27
* T29
* T49

There would ideally be another mean to easily differentiate between the
support level of the different models...

These are not "officially supported devices", so don't add them in the
plugin description.

Seems like it's official "code name" is VP-T49G, but we'll call it T49G.

Did no test other than plugging the phone.