Check size

• apifun_checkdims — Generates an error if the variable has not the required size.
• apifun_checkscalar — Generates an error if the variable is not a scalar.
• apifun_checksquare — Generates an error if the variable is not a square matrix.
• apifun_checkveccol — Generates an error if the variable is not a column vector.
• apifun_checkvecrow — Generates an error if the variable is not a row vector.
• apifun_checkvector — Generates an error if the variable is not a vector.