collapse multiple empty lines into a single empty line

doc/src/Python_install.rst

@@ -31,7 +31,6 @@ If you set the paths to these files as environment variables, you only
 have to do it once.  For the csh or tcsh shells, add something like
 this to your ~/.cshrc file, one line for each of the two files:
 
-
 .. parsed-literal::
 
    setenv PYTHONPATH ${PYTHONPATH}:/home/sjplimp/lammps/python
@@ -49,7 +48,6 @@ files are updated with the new version.
 If the default settings of "make install-python" are not what you want,
 you can invoke install.py from the python directory manually as
 
-
 .. parsed-literal::
 
    % python install.py -m \<python module\> -l <shared library> -v <version.h file> [-d \<pydir\>]