t.info: add format option and support for JSON output

[ninsbl]

t.info returns a relatively complex metadata for Space Time Datasets. As of now, JSON output is not yet supported.

t.info should be able to return JSON format, this a format option and JSON output (possibly YAML and others) should be added.

The most elegant solution may be to add a print_json (or print_yaml, ...) method to:

grass/python/grass/temporal/abstract_dataset.py

Lines 213 to 224 in 8d98e10

	@abstractmethod
	def print_info(self):
	"""Print information about this class in human readable style"""
	@abstractmethod
	def print_shell_info(self):
	"""Print information about this class in shell style"""
	@abstractmethod
	def print_self(self):
	"""Print the content of the internal structure to stdout"""

And the subsequent dataset types...

[HUN-sp]

Hi @ninsbl, I would like to work on this. I can implement the print_json method in abstract_dataset.py using the standard Python json library to serialize the dataset metadata.

I will start by reviewing the existing print_info method to map the attributes correctly