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
