Bug fixes before merging develop into main

[hannahgoerigk]

While working through the districtgenerator installation we found these bugs:

1. setup.py
   When installing districtgenerator as local package, reportlab was missing.
   Solution: Adding 'reportlab~=3.6.13' to requirements.txt

2. envelope.py
   We found an unused variable "heatCapacity or C_m" in method calcNormativeProperties. Might be still under development and therefore unused. Maybe check if necessary.
   -> in develop-branch (77b1c94): districtgenerator/classes/envelope.py:539

3. envelope.py
   Added comments regarding norm values inside calcHeatLoad.
   After revision, they might be added to the master. Changes were first made inside aix_heat_dev-branch.

Proposition:

    def calcHeatLoad(self, site, method="design"):
        """
        Calculate design (nominal) heat load at norm outside temperature following DIN EN 12831-1 / DIN/TS 12831-1.

        Parameters
        ----------
        site : dict
            Information about location and climate conditions.
        method : string, optional
            Method to calculate heat load. The default is "design".

        Returns
        -------
        Q_nHC : float
            Heat load.
        """

        # Thermal bridge surcharge for opaque components (categroy A) [table 2, DIN/TS 12831-1]
        U_TB = 0.05  # [W/m²K]
        # Correction factor for annual fluctuation of the outdoor temperature (fθann) [DIN/TS 12831-1, 4.3.1]
        f_g1 = 1.45
        # Reduction factor (fix,k) [DIN EN 12831-1, 6.3.2.5 and table 7]
        # T_me = mean outdoor temperature
        # T_ne = norm outdoor temperature
        # for an exterior wall f1 = 1 -> fix,k = f1 + f2 = f2
        f_g2 = (self.T_set_min - site["T_me"]) / (self.T_set_min - site["T_ne"])
        # influence of groundwater neglected [DIN/TS 12831-1, 4.3.1]
        G_w = 1.0

[hannahgoerigk]

As far as I see everything on this list is now adjusted / fixed.