Capital letter of parameter "ExcDir"

[mariok90]

It seems inconsistent compared to the rest of the parameters which all start with a lower case.

Limits on exchange

Limits on exchange quantities. In the inheritance rules sum* only applies for upper limits.

name	exc{Fix/Low/Up}	ExcDir{Fix/Low/Up}
unit	GWh
dimension	$Ts_{dis}$, $R_{a}$, $R_{b}$, $C$
default value	none
inheritance rules	$Ts_{dis}$ → sum/sum* $R_{a}$ → sum/sum* $R_{b}$ → sum/sum* $C$ → sum/sum*
related elements	see limiting constraints
part	limit

Suggestion change ExcDir to excDir to be in line with the other parameters.