Issue523 s1l2 mapper

[korvinos]

New mapper for s1 iw l2 data with the support of the owi and rvl products

[akorosov]

Can you fix two things: key word args explicitly in the init defintion and context manager for Dataset() ?

[akorosov]

Suggested change

	def __init__(self, file_src, gdal_dataset, gdal_metadata, *args, **kwargs):
	def __init__(self, file_src, gdal_dataset, gdal_metadata, subswath_id=0, product='rvl', dop_time = False, **kwargs):

Like in : https://github.com/nansencenter/nansat/blob/master/nansat/mappers/mapper_sentinel1_l1.py

[akorosov]

Suggested change

	# Check if the subswath number [1, 2, 3] is provided
	# Subswath number is required for mapping the RVL products
	if 'subswath_n' in kwargs.keys():
	subswath_id = kwargs['subswath_n'] - 1
	else:
	subswath_id = 0
	# Check if the product type is provided: rvl
	if 'product_type' in kwargs.keys():
	product = kwargs['product_type']
	else:
	product = 'rvl'
	if 'dop_time' in kwargs.keys():
	dop_time = kwargs['dop_time']
	else:
	dop_time = False

[akorosov]

If something goes wrong nc is not closed -potential memory leak.
Its is better to always use

with Dataset(file_src) as nc_dataset:
    all_the_data = nc_dataset['all_the_data']