Added expansion vessel and updated documentation of ConservationEquation.

This is for #42.
Added expansion vessel reference results.

This is for #42.
Merge branch 'master' into issue42_expansionVessel
HydraulicTest: comparison of a simple hydraulic test using Annex60Water and Modelica ConstantPropertyWater + problem with step temperature with dynamic pipe
revert unuseful changes compare to master
Merged actuators from Buildings to Annex60 library.

This is for #51.
Merge pull request #47 from iea-annex60/issue42_expansionVessel

Merge Issue42 expansion vessel - tested in Buildings library and no objections from my side
Merge pull request #52 from iea-annex60/issue51_actuators

Merged actuators from Buildings to Annex60 library. All examples work and code looks correct
Added missing packages to package.order.
Corrected malformed documentation which caused model not to load in OpenModelica.
Correct typo in cp of water #54

The specific heat capacity of water has been given as cp_const = 4148.
This is changed to cp_const = 4184.
Merge branch 'master' into issue54_cpWater
Updated reference results due to change in cp of water.
Merge pull request #55 from iea-annex60/issue54_cpWater

Issue54 cp water
Merge remote-tracking branch 'remotes/upstream/master' into issue50_hydraulicTest
add some simple examples to illustrate the difference between Annex60.Media.Water and Modelica.Media.Water.ConstantPropertyLiquidWater.