MagPy Version 0.4.6

####v<0.4.6>, <2018-02-01> --

v0.4.6 general:
+ PYCDF format - changed time format from EPOCH to TT2000

v0.4.6 fixes:
+ writeDB - resolution in timecolumns changeable by roundtime variable
+ GUI - polynomial fit now working in GUI
+ writeDB: method will now work even for very large datasets
+ GUI: freezing error when double clicking solved
+ writeDB: treatment of columns with only nan values has been corrected
+ GUI: when opening multiple data set: sorting by time column
+ FlagOutlier: combination of susequent time steps corrected -
previously some flags were lost when saving and reloading
+ database: understandable error messages
+ trim: corrections if stream outside the timerange
+ python3 import of IYFV files now possible

v0.4.6 additions:
+ added method 'cut' to extract lines from a stream from the beginning or end
+ updated import library for ionometer
+ GUI: added better names + dates to Streamlist operations
+ GUI: streamlist is now scrollable