global-functions: implement notifications via Matrix

Matrix is an open network for secure, decentralized communication - and
it has a web api.

A warning on message type: Using 'm.notice' breaks rendering on Element
for Android (no fixed width font) and does not pop up desktop
notification. Thus we use 'm.text'. Should be safe as we do not send the
messages in response to other messages.

https://matrix.org/

doc/check-certificates.md

@@ -22,8 +22,8 @@ Just install the script:
 Configuration
 -------------
 
-The expiry notifications just require notification settings for e-mail and
-telegram.
+The expiry notifications just require notification settings for e-mail,
+matrix and/or telegram.
 
 For automatic download and renewal of certificates you need configuration
 in `global-config-overlay`, these are the parameters:

doc/check-health.md

@@ -39,7 +39,7 @@ The configuration goes to `global-config-overlay`, These are the parameters:
 * `CheckHealthTemperature`: an array specifying temperature thresholds for sensors
 * `CheckHealthVoltagePercent`: percentage value to trigger voltage jumps
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 ---
 [◀ Go back to main README](../README.md)  

doc/check-lte-firmware-upgrade.md

@@ -31,7 +31,7 @@ Just install the script:
 Configuration
 -------------
 
-Notification setting are required for e-mail and telegram.
+Notification setting are required for e-mail, matrix and/or telegram.
 
 See also
 --------

doc/cloud-backup.md

@@ -26,7 +26,7 @@ The configuration goes to `global-config-overlay`, these are the parameters:
 * `BackupPassword`: password to encrypt the backup with
 * `BackupRandomDelay`: delay up to amount of seconds when run from scheduler
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 Usage and invocation
 --------------------

doc/collect-wireless-mac.md

@@ -36,7 +36,7 @@ On first run a disabled access list entry acting as marker (with comment
 "`--- collected above ---`") is added. Move this entry to define where new
 entries are to be added.
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 Usage and invocation
 --------------------

doc/daily-psk.md

@@ -47,7 +47,7 @@ Then add an access list entry:
 
     / interface wireless access-list add comment="Daily PSK" interface=wl-daily private-pre-shared-key="ToBeChangedDaily";
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 ---
 [◀ Go back to main README](../README.md)  

doc/log-forward.md

@@ -39,7 +39,7 @@ The configuration goes to `global-config-overlay`, these are the parameters:
 * `LogForwardFilter`: define topics *not* to be forwarded
 * `LogForwardFilterMessage`: define message text *not* to be forwarded
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 ---
 [◀ Go back to main README](../README.md)  

doc/netwatch-notify.md

@@ -61,7 +61,7 @@ But be warned: Dynamic updates will probably cause issues if the name has
 more than one record in dns - a high rate of configuration changes (and flash
 writes) at least.
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 Tips & Tricks
 -------------

doc/sms-forward.md

@@ -27,8 +27,8 @@ Just install the script:
 Configuration
 -------------
 
-Notification settings are required for e-mail and telegram. Also you have
-to enable receiving of SMS:
+Notification settings are required for e-mail, matrix and/or telegram. Also
+you have to enable receiving of SMS:
 
     / tool sms set receive-enabled=yes;
 

doc/upload-backup.md

@@ -32,7 +32,7 @@ The configuration goes to `global-config-overlay`, these are the parameters:
 * `BackupUploadUser`: username for server authentication
 * `BackupUploadPass`: password for server authentication
 
-Also notification settings are required for e-mail and telegram.
+Also notification settings are required for e-mail, matrix and/or telegram.
 
 ### Issues with SFTP client