Passing CRAN checks

[klr324]

Obsdbr was checked based on R CRAN checks R CMD check --as-cran obsdbr_0.0.0.9.tar.gz and updated accordingly to pass the checks.

Full updates include (as provided in NEWS.md): Changes:

• Housekeeping changes: added NEWS (including retroactive listing of changes) and cran-comments file.
• Change of obsdbr maintainer
• Added some function examples based on those in the original README
• Added singularity definition file for testing package development

Addressed CRAN-COMMENTS:

• Fixed: Version contains large components (0.0.0.9000) ==> 0.0.0.9 (numbers must be between 1-9).
• Fixed: The Title field should be in title case.
• Fixed: Non-standard license specification: GNU General Public License v3.0 ==> GPL-3
• Fixed: '::' or ':::' imports not declared from: ‘xts’ ‘zoo’ ==> declared imports in NAMESPACE
• Fixed: Undefined global functions or variables: 'aggregate.data.frame' 'as.formula' ==> declared imported functions
• Fixed: Undocumented arguments:
  • in 'coerce_spacewide_xts_to_STFDF': ‘xts_sw’ ‘spdf_locs’ ‘varname’
  • in 'coerce_tidy_df_to_spacewide_xts': ‘df_tidy’ ‘value.var’ ‘time_col’ ‘id_col’