adding calculus-grapher (see https://github.com/phetsims/calculus-grapher/issues/50)
adding calculus-grapher (see https://github.com/phetsims/calculus-grapher/issues/50)

Signed-off-by: Martin Veillette <f12556599ad0faf95576b4a500c046f07412451d@gmail.com>

phetsims/perennial,phetsims/perennial,phetsims/perennial