Issue in get/read_bsrn naming of variables in logical record 0500

[AdamRJensen]

Describe the bug
The list of column names for the logical record LR0500 in the get/read_bsrn iotools function contains duplicate column names. Specifically, "uvb_diffuse" and "uvb_diffuse_std" appear twice.

The station-to-archive format is described on page 12 of this document.

pvlib-python/pvlib/iotools/bsrn.py

Lines 42 to 51 in 7fb3a0e

	BSRN_LR0500_COLUMNS = ['day', 'minute', 'uva_global', 'uva_global_std',
	'uva_global_min', 'uva_global_max', 'uvb_direct',
	'uvb_direct_std', 'uvb_direct_min', 'uvb_direct_max',
	'empty', 'empty', 'empty', 'empty',
	'uvb_global', 'uvb_global_std', 'uvb_global_min',
	'uvb_global_max', 'uvb_diffuse', 'uvb_diffuse_std',
	'uvb_diffuse', 'uvb_diffuse_std',
	'uvb_diffuse_min', 'uvb_diffuse_max',
	'uvb_reflected', 'uvb_reflected_std',
	'uvb_reflected_min', 'uvb_reflected_max']

Description of LR0500

[AdamRJensen]

I think the solution is to delete line 48 above. However, it is not clear to me whether the "upward reflected" measurements are UVA or UVB?

Edit: in the 2005 BSRN manual this was not specified, but it was clarified in the 2013 update.