Task/TaskFileSeeYou: Handle trailing ',' in task entries

Some versions of StrePla write a trailing ',' in task entries, e.g.

"KORBACH/SCHWARZENBACH","KEMPEN","KEMPEN","KORBACH","SCHWARZE","KEMPEN","KEMPEN",

Handle this case correctly.
Android/I2Cbaro: close the EOC DigitalInput

Fixes "java.lang.IllegalArgumentException: Resource already claimed"
when pressing the reconnect button.
AirspaceParser: move code to ParseBearingDegrees()
AirspaceParser: use ParseDouble()
XML/DataNode: use ParseDouble()
Dialogs/XML: use ParseDouble()
AirspaceParser, AngleDataField: omit the optional ParseDouble() parameter

nullptr is the default value.
Util/NumberParser: work around mingw64 wcstod() bug

mingw64 version 3.1 crashes when the "endptr" argument to wcstod() is
nullptr.  This patch adds another wrapper function which passes a
dummy parameter instead of nullptr.  This fixes instant crashes of our
6.7.4 PC binary (TRAC #3284).
po: update Romanian translation
po: update Slovak translation
release v6.7.5
Merge tag 'v6.7.5'