getWindowsCodePage is taken from Grass7Utils.py
Instead of writing a cli_file at startup, provider now pass all
required env_variables directly to subprocess.popen. This has known to
cause issues when handling with windows path names. subprocess.Popen
handles it correctly depending on platform
Logging of output from otbalgorithm and updating progress bar is
slightly updated.
Algoirthm is now launched directly using otbApplicationLauncherCommandLine
`encoding` (on windows) and env arguments passed to subprocess is
logged in QgsMessageLog
OTB only supports gdal and ogr providers for now. Maybe memory
provider can be easily supported using some conversion on the fly.
For the moment, we can go with this method. IO Formats in OTB not
using GDAL/OGR (LUM, ONERA) are not supported by QGis. Those can be
treated as simple files.
nyalldawson, pointed that AUTHORITY id can have types not starting
with 'EPSG:'. Current otb takes just EPSG number and run with it. The
algorithm doesn't know what to with a number which is not EPSG because
it uses Gdal's 'ImportFromEpsg' method AFAIR.
QgsProecessing Exception is raised in both the above invalid cases.
