bump version to 13.23
update information on Digium D70 device
suppressed warning for unimplemented user-voicemail disassociation
update information on Yealink T46G device
document readonly-idpwd in ipbx.ini
document missing fields in REST API 1.1 users
fix minor style issues in RESTAPI 1.1 users
update sheet documentation
add missing files
add new widgets supported in sheets
fix grammar style
Merge pull request #2 from xivo-pbx/4741-ipbxini

document readonly-idpwd in ipbx.ini
add qlabel and qplaintextedit to sheets
add variables to custom sheets
remove reference to 1.2 version
use /var/tmp in the examples instead of /tmp since, on a default XiVO installation, 90% of the disk is assigned /var. Add also warning to check the disk free space.
Merge branch 'master' of github.com:xivo-pbx/xivo-doc
[cti protocol] added stat messages
update information on Yealink T46G device
update information on Yealink T42G device