add curly braces support to mqtt integration, documentation

contrib/etc/ebusd/mqtt-integration.cfg

@@ -6,6 +6,7 @@
 # where only the value is allowed to contain references to other variables.
 # A reference to a variable is escaped by a leading "%" character in front of the variable name consisting of only
 # alphabetic characters or the underscore. A double percent character "%%" is replaced by a single "%" in the value.
+# Curly braces may be used to separate a variable explicitly from the rest, e.g. as "%{version}" instead of "%version".
 # Every variable without an underscore in the name is automatically made available as well with an uppercase name and a
 # normalized value composed of only alphanumeric characters or underscore (i.e. suitable for being part of a topic).
 # When using "?=" instead of only the equal sign in a variable definition, the variable value is set to empty when one
@@ -93,12 +94,10 @@ filter-direction = r|u
 #filter-field =
 
 
-
 # the field type mapped from variables named "type_map-%direction-%type" or "type_map-%type" as fallback with the
 # field type and the optional direction in the suffix. The variable including the direction is evaluated first and
 # if it is missing or the result is empty, the variable excluding the direction is used instead.
 # This is also an implicit field type filter as missing or empty mappings are not published at all.
-
 type_map-number = number
 type_map-list = string
 type_map-string = string
@@ -107,6 +106,30 @@ type_map-time = string
 type_map-datetime = string
 
 
+# field type switch designator, see below.
+#type_switch-by = %name%field,%unit
+
+# field type switch variables names to use in addition to %type_switch in case of multiple keys (separated by comma).
+#type_switch-names = type_topic,type_class,type_state
+
+# field type switch for each field type and optionally direction (between dash before the field type) available as
+# %type_switch (as well as the variable names defined in "type_switch-names" if any).
+# The value needs to be a constant list of string pairs with one pair per line. Each pair is separated by "=" and the
+# left part is the value set to the type_switch variable (as well as the variable names defined in %type_switch-names)
+# when the wildcard string in the right part matched the "type_switch-by" value. The list is traversed from top to
+# bottom stopping at the first match. If direction specific definitions exist, these are traversed first. If no line
+# matches at all, the variable(s) are set to the empty string.
+#type_switch-w-number =
+
+
+# field type part suffix to use instead of the field type itself, see below.
+#type_part-by = %type_topic
+
+# field type part mappings for each field type (or the "type_part-by" variable value) in the suffix (available as
+# %type_part).
+#type_part-number = ,
+
+
 # the message definition config topic, payload, and retain setting.
 definition-topic = %prefixn/config/%CIRCUIT/%NAME/%FIELD
 definition-payload = {