Develop metadata missing dat

See merge request !106

Develop largest dim length

See merge request !107

Add new params 'largest_dims_length' to determine if Start() should examine all the files to get the dim or not

Set the result of nchar() to 0 if it is integer(0)

See merge request !104

Add one 'if' condition to ensure the first file of each dataset exists. If not, metadata is assigned to NULL.

Fix metadata reading bug when certain dataset is missing

See merge request !105

Develop unittest fix

See merge request !103

# Conflicts:
#   NEWS.md

cleaning added to Chunk.ecf

See merge request !102