Rename types of branch loading

src/PowerFlow.jl

-#* Functions for calculating the power flow in a power grid described by NDD
+#* Functions for calculating the power flow in a power grid described by a NDD
 #*------------------------------------------------------------------------------
 
 #=
@@ -97,7 +97,7 @@ function calc_branchloads!(network_data::Dict{String,<:Any}; model=:ac)
             mw_to = sqrt(branch["pt"]^2)
             ### Add active power flow to branchloads
             branchloads["branch"][i] = Dict(
-                "MW_loading" => max(mw_fr, mw_to) / branch["rate_a"]
+                "MW-loading" => max(mw_fr, mw_to) / branch["rate_a"]
             )
         elseif model == :ac # AC-PF
             ### Active power flow
@@ -111,9 +111,9 @@ function calc_branchloads!(network_data::Dict{String,<:Any}; model=:ac)
             mva_to = sqrt(branch["pt"]^2 + branch["qt"]^2)
             ### Add all flows to branchloads
             branchloads["branch"][i] = Dict(
-                "MW_loading" => max(mw_fr, mw_to) / branch["rate_a"],
-                "Mvar_loading" => max(mvar_fr, mvar_to) / branch["rate_a"],
-                "MVA_loading" => max(mva_fr, mva_to) / branch["rate_a"]
+                "MW-loading" => max(mw_fr, mw_to) / branch["rate_a"],
+                "Mvar-loading" => max(mvar_fr, mvar_to) / branch["rate_a"],
+                "MVA-loading" => max(mva_fr, mva_to) / branch["rate_a"]
             )
         else
             throw(ArgumentError("Unknown model $model."))