When a format has no pre-recorded sound files, Asterisk has to transcode between
formats. For this, Asterisk has a fixed translation table. If the pre-recorded
sound files are not available in the same sample rate, Asterisk has not only to
transcode but also to resample.

Asterisk has pre-recorded files for SLN (8000 kHz) and SLN16 (16000 kHz).
However before this change, Asterisk did not take the sample rate into account,
because the translation paths to SLN and SLN16 got the same score/weight in the
table. Consequently, you might have got narrow-band audio with siren14, speex32,
silk24, and silk12 although those are (ultra) wide-band audio codecs.

With this change, the distance in sample-rates is taken into account. Now on the
Command-Line interface (CLI) 'core show channels', you should see:
(slin@16000)->(slin@32000)->(speex@32000).

ASTERISK-23735
Reported by: Richard Kenner

Change-Id: I9448295c1978be26f8633b6066395e7bbbe2e213

Previously, Asterisk sent srflx only when configured exclusively for IPv4. Now,
srflx is gathered and sent via SDP, even when Asterisk is enabled for
Dual Stack (IPv4+IPv6) and an IPv4 interface is available/used.

ASTERISK-27437

Change-Id: Ie07d8e2bfa7b6fe06fcdc73d390a7a9a4d8c0bc1

res_parking had an inplicit load_pri of 0 meaning it was one of the very
first modules loaded after modules with global symbols.  Set it to
AST_MODPRI_DEVSTATE_PROVIDER as it provides device state for parking
lots.

Change-Id: I297b6fb3ff6993ec004e667b22a74f5925906259

Convert the README file to markdown format, remove the old README.  This
causes websites like github to display the README in a much nicer
format with live links.  The raw file is still very readable from
plain text editors and terminals.

Change-Id: I7d13131764a9a9026e5f8a6ddb245a01bbd788e7

ASTERISK-27434

Change-Id: Iaeed89b4fa05d94c5f0ec2d3b7cd6e93d2d5a8f7

Make the comments follow doxygen format, move comments to the line
before each field they describe.

Change-Id: Ic445468398b5e88f13910f7c2f70bd15aad33a27

Change-Id: I81aacfee7cd26e4fc5eef07bca582700c2975bd7

Change-Id: I5ce40035e0a940e4e56f6322c1dcd47fbd509b98

Change-Id: Ideb594f7aae134974fb78d5477ba0853b97b8625

Change-Id: I07907f833b81aeb0128bc9442a2abb52679c7511

Change-Id: I9d56175369363d1dc735504cf78a3a5577069f49

res_mwi_external_ami specified AST_MODFLAG_LOAD_ORDER but didn't set
load_pri, resulting in an actual load priority of 0.  This module only
provides AMI actions so it has no reason to load early.

Change-Id: I82987fcf10d3ea42716b2f9df915b16687fd5839

Instead of specifying AST_MODFLAG_LOAD_ORDER with load_pri
AST_MODPRI_DEFAULT just use AST_MODFLAG_DEFAULT.

Change-Id: I0123258eafce324249433a69df15a85cc16e509f