Feature het code in pdb from smiles

[Jgmedina95]

Hi! this is the first part of the PRs needed to get the simulation working for systems with solvents different than water.
Basically makes it such that the pdb file downloaded from the smiles for small molecules goes from:

HETATM    1  C1  UNL     1      -0.360  -0.003  -0.018  1.00  0.00           C  
HETATM    2  O1  UNL     1       0.914   0.522  -0.078  1.00  0.00           O  
HETATM    3  H1  UNL     1      -0.490  -0.816  -0.757  1.00  0.00           H  
HETATM    4  H2  UNL     1      -0.615  -0.390   0.996  1.00  0.00           H  
HETATM    5  H3  UNL     1      -1.069   0.834  -0.202  1.00  0.00           H  
HETATM    6  H4  UNL     1       1.619  -0.147   0.060  1.00  0.00           H  
CONECT    1    2    3    4    5
CONECT    2    6
END

to

COMPND    ethanol
HETATM    1  C1  EOH     1      -0.953   0.048   0.042  1.00  0.00           C  
HETATM    2  C2  EOH     1       0.489  -0.320  -0.189  1.00  0.00           C  
HETATM    3  O1  EOH     1       1.277   0.325   0.738  1.00  0.00           O  
HETATM    4  H1  EOH     1      -1.357   0.734  -0.733  1.00  0.00           H  
HETATM    5  H2  EOH     1      -1.593  -0.863   0.022  1.00  0.00           H  
HETATM    6  H3  EOH     1      -1.071   0.596   1.011  1.00  0.00           H  
HETATM    7  H4  EOH     1       0.788  -0.138  -1.238  1.00  0.00           H  
HETATM    8  H5  EOH     1       0.590  -1.429  -0.041  1.00  0.00           H  
HETATM    9  H6  EOH     1       1.831   1.047   0.388  1.00  0.00           H  
CONECT    1    2    4    5    6
CONECT    2    3    7    8
CONECT    3    9
END

[qcampbel]

made some minor suggestions. Overall, LMTG. Thanks for adding this!