use EMAMOpt2CPP instead of EMAM2CPP

2 jobs for use_math_opt_generator in 3 minutes and 47 seconds (queued for 3 seconds)
latest
Status Job ID Name Coverage
  Windows
passed masterJobWindows #270135
Windows10

00:02:13

 
  Linux
passed BranchJobLinux #270136

00:01:34