Check that statically declared 3-dimensional arrays are allowed in McCode 3 COMP grammar

[willend]

From debugging-session with Steffen Sloth it seems that current COMP grammar only handles

DECLARE %{
     int oned[nx];
     int twod[nx][ny];
     // but not int threed[nx][ny][nz];
%}

The grammar should allow for 3d definitions, and we should further consider int versions of the DArrayXd types /functions/etc