Re: Allow quoted identifiers like to be used like \"violin1", not just defined. (issue 6778055)

[k-ohara5a5a]

Well, David has pointed out some shortcomings, but I am not sure if they
are practical problems.

The strings in
  "violin1" = c2   { "\violin1" }
must be literal strings, whereas most other places we can
build strings in Scheme.  So the instrumentName setting here works, but
the corresponding variable names do not
  $(format #f "violin~a" 2) = {c' d' e' f'}
  \new Staff \with {
     instrumentName = $(format #f "Violin ~a" (+ 1 1))
  } \$(format #f "violin~a" (+ 1 1))
So the superficial similarity with strings breaks down as soon as you
try putting it to the test.

The valid names for identifiers are no longer a simple lexer pattern,
but anything that can be put between quotes, making syntax highlighting
more difficult.
  "\\" = c''1  { \"\\" }

There is apparently a more powerful array implementation in the works,
that will allow simply \violin1

And finally, we have the choice discussed above between code-duplication
and abuse of the Flex start-condition system.

By comparison, a simple change to the scan patterns
http://codereview.appspot.com/6493072/diff/19001/lily/lexer.ll
would be much cheaper and better-confined.

http://codereview.appspot.com/6778055/