Updated "jar.async.Value"

value.forwardTo() now stops every forwarding when the value
that is forwarded to freezes.
Updated value.delay() to use value.forwardTo()
Fixed behaviour of throttle() and debounce()
Refactored value.throttle() and value.debounce()

Now uses methods of "jar.lang.Function.Function-guards".
Added constant
Updated to use "jar.lang.Constant"
Changes in "jar"

Config inheritance for modules configuration.
JAR.main(), configure(), $import() and $export() return this for chaining.
Minor fixes.
Extracted code as mixins

"jar.async.Value.M$Acceptable"
"jar.async.Value.M$Forwardable"
"jar.async.Value.M$Mappable"