Create make.bat for building sphinx docs on Windows (#981)

* Create make.bat

* whatsnew

* resolve sapm2 equation name conflict

Author: kandersolar

docs/sphinx/make.bat

@@ -0,0 +1,35 @@
+@ECHO OFF
+
+pushd %~dp0
+
+REM Command file for Sphinx documentation
+
+if "%SPHINXBUILD%" == "" (
+	set SPHINXBUILD=sphinx-build
+)
+set SOURCEDIR=source
+set BUILDDIR=build
+
+if "%1" == "" goto help
+
+%SPHINXBUILD% >NUL 2>NUL
+if errorlevel 9009 (
+	echo.
+	echo.The 'sphinx-build' command was not found. Make sure you have Sphinx
+	echo.installed, then set the SPHINXBUILD environment variable to point
+	echo.to the full path of the 'sphinx-build' executable. Alternatively you
+	echo.may add the Sphinx directory to PATH.
+	echo.
+	echo.If you don't have Sphinx installed, grab it from
+	echo.http://sphinx-doc.org/
+	exit /b 1
+)
+
+%SPHINXBUILD% -M %1 %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+goto end
+
+:help
+%SPHINXBUILD% -M help %SOURCEDIR% %BUILDDIR% %SPHINXOPTS% %O%
+
+:end
+popd

docs/sphinx/source/whatsnew/v0.8.0.rst

@@ -44,6 +44,8 @@ Documentation
 * Clarify units for heat loss factors in
   :py:func:`pvlib.temperature.pvsyst_cell` and
   :py:func:`pvlib.temperature.faiman`. (:pull:`960`)
+* Add make.bat so that docs can be built on Windows without ``make`` installed.
+  (:issue:`978`, :pull:`981`)
 * Add instructions to build the documentation. (:pull:`982`)
 * Corrected key names for :py:func:`pvlib.inverter.sandia`. (:issue:`976`,
   :pull:`886`)

pvlib/temperature.py

@@ -213,7 +213,7 @@ def sapm_cell_from_module(module_temperature, poa_global, deltaT,
         Total incident irradiance [W/m^2].
 
     deltaT : float
-        Parameter :math:`\Delta T` in :eq:`sapm2` [C].
+        Parameter :math:`\Delta T` in :eq:`sapm2_cell_from_mod` [C].
 
     irrad_ref : float, default 1000
         Reference irradiance, parameter :math:`E_{0}` in
@@ -228,7 +228,7 @@ def sapm_cell_from_module(module_temperature, poa_global, deltaT,
     The model for cell temperature :math:`T_{C}` is given by Eq. 12 in [1]_.
 
     .. math::
-       :label: sapm2
+       :label: sapm2_cell_from_mod
 
        T_{C} = T_{m} + \frac{E}{E_{0}} \Delta T