Include location of errors

[dsherret]

There are several errors on LexerError that would probably benefit from having the location on them (maybe all of them?)

merve/rust/src/lib.rs

Lines 40 to 56 in 56ae38b

	pub enum LexerError {
	EmptySource,
	UnexpectedParen,
	UnexpectedBrace,
	UnterminatedParen,
	UnterminatedBrace,
	UnterminatedTemplateString,
	UnterminatedStringLiteral,
	UnterminatedRegexCharacterClass,
	UnterminatedRegex,
	UnexpectedEsmImportMeta,
	UnexpectedEsmImport,
	UnexpectedEsmExport,
	TemplateNestOverflow,
	/// An error code not recognized by these bindings.
	Unknown(i32),
	}