Refactor host command-line parsing
Refactor host command-line parsing

Supports a syntax more similar to powershell.exe on Windows, with --file
and --command options, as well as the automatic execution of a script by
name, or a command via string. Prepares for reading of stdin.

daxian-dbw/PowerShell,bingbing8/PowerShell,TravisEz13/PowerShell,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,TravisEz13/PowerShell,JamesWTruher/PowerShell-1,bmanikm/PowerShell,kmosher/PowerShell,PaulHigin/PowerShell,bingbing8/PowerShell,bmanikm/PowerShell,KarolKaczmarek/PowerShell,bmanikm/PowerShell,kmosher/PowerShell,TravisEz13/PowerShell,PaulHigin/PowerShell,kmosher/PowerShell,jsoref/PowerShell,bingbing8/PowerShell,jsoref/PowerShell,bmanikm/PowerShell,jsoref/PowerShell,jsoref/PowerShell,TravisEz13/PowerShell,bingbing8/PowerShell,JamesWTruher/PowerShell-1,kmosher/PowerShell,KarolKaczmarek/PowerShell,PaulHigin/PowerShell,PaulHigin/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,KarolKaczmarek/PowerShell,bingbing8/PowerShell,kmosher/PowerShell,bmanikm/PowerShell,KarolKaczmarek/PowerShell,daxian-dbw/PowerShell,JamesWTruher/PowerShell-1,jsoref/PowerShell