remove pvsystem.systemdef function

[wholmgren]

Does anyone use this function? Does anyone have use case for it? I'm inclined to remove it without deprecation in 0.8.

Another option is to move it to pvlib.iotools.tmy.

[mikofski]

I don't use it, I had to search pvlib for systemdef

code:

• pvlib-python/pvlib/pvsystem.py

  Line 894 in f8921bd

  def systemdef(meta, surface_tilt, surface_azimuth, albedo, modules_per_string,

relevant issues:

• meta, location, and systemdef philosophy #17

relevant tests:

• pvlib-python/pvlib/tests/test_pvsystem.py

  Line 22 in 03d6180

  def test_systemdef_tmy3():

• pvlib-python/pvlib/tests/test_pvsystem.py

  Line 39 in 03d6180

  def test_systemdef_tmy2():

• pvlib-python/pvlib/tests/test_pvsystem.py

  Line 57 in 03d6180

  def test_systemdef_dict():

docs:
api.rst