convert-ly 2.4.3 shortcomings

[Fairchild]

Just converted a couple of 2.0.1 files to 2.4.3.  Most changes are OK, but
here are some things convert-ly left as an exercise for the student.

1) New version number isn't correct.
    - \version "2.4.0" => \version "2.4.3"

2) In 2.4.3, an ordinary slur won't cross acciaccatura.  It's not corrected.
    - Ordinary slur ( . . . ) crossing acciaccatura =>  use \( . . . \)

3) \magnify isn't changed to \fontsize.
    - \magnify #m => \fontsize #f, where f = 8.656 ln(m), easy to do with a
Post VERSALOG
        [ a^f = m, where  a^6 = 2 or f = ln(m)/ln(a) ]

4) remove-tag isn't changed.
    - \applymusic #(remove-tag '. . .) => \keepWithTag #'. . .

5) firstpagenumber isn't changed.
    - firstpagenumber no => printfirstpagenumber = ##f

6) Tilde is printed in 2.4.3.  Blank characters are accepted in 2.4.3.
    - Tilde "~" as blank in text strings => " ", blank now accepted, or ""

7) Line breaks in header strings aren't converted.
    - \\\\  as line break in \header strings => \markup \center-align <
"First Line" "Second Line" >

8) Crescendo and decrescendo terminators aren't converted.
    - \rced => \!
    - \rc => \!

                                      - Bruce