cleaned trailing blanks; revised the import method: removed unnecessary vars, added comments, added default data dir (when files are passed without path), implementing importing GRACE L1B data (with help from grace-data scripts), moved L1B data parsing to dedicated functions
cleaned trailing blanks; revised the import method: removed unnecessary vars, added comments, added default data dir (when files are passed without path), implementing importing GRACE L1B data (with help from grace-data scripts), moved L1B data parsing to dedicated functions

jgte/orb,jgte/orb,jgte/orb,jgte/orb,jgte/orb