Encode LF in #.fmfn

FileMaker's Value functions treat CR and LF as equivalent, but the
Quote function does not.  There's no FileMaker escape sequence for LF.

For example:
  ValueCount ( Quote ( Quote ( List ( "a" ; "b" ; Char ( 10 ) ; "c" )
  ) ) ) // Returns 2, expected 1

As a result, # will return invalid Let notation for values containing
LF.  This problem doesn't appear when using #Get, which doesn't rely
on value list processing.  However, #Filter fails spectacularly on
this invalid result.

The trick is to encode LF.  We can do this similarly to how we encode
timestmaps.  We Substitute LF for a string concatenation with
"Char ( 10 )".

https://github.com/filemakerstandards/fmpstandards/issues/7

Discussed with https://github.com/dansmith65