Use only supported log levels for command line option. (#14406)
When starting NVDA with an unsupported command line parameter, you get the following suggestion for log level in the error message:
[-l {10,12,15,20,30,40,50,100}]
Launching NVDA with log level set to 30, 40 or 50 actually indicates NVDA using info level.
Description of user facing changes
Only supported log levels are indicated in the error message when a wrong parameter is passed to NVDA.
Only supported log level can now be used from command line, i.e. 10=debug, 12=I/O, 15=debugWarning, 20=info and 100=off
Description of development approach
Changed the information passed to the command line parser.
While at it, changed default from "en" to "Windows" in the parser's --lang parameter; this seem to have no impact however since "Windows" was already used when this parameter is missing.
