Teach the lexer to return tokens for whitespace. Teach the parser to
tolerate the space tokens where whitespace is allowed. Also teach the
parser to diagnose and warn about cases of quoted arguments followed
immediately by another argument. This was accidentally allowed
previously, so we only warn.
Update the RunCMake.Syntax test case StringNoSpace expected stderr to
include the warnings.
Test basic unquoted and quoted argument parsing cases including failure
on an unterminated string and an unterminated command invocation. Also
cover arguments not separated by any spaces, which is accidentally
allowed by the current parser.
Stephen Kelly
Brad King