A small bug in gemme.py about user provided pdb files was corrected.

If the user does not provide a pdbfile and asks the program to calculate
structural-dynamical parameters like Bfactor, CV or DFI, the program will
give an error and quit. Before, there was not such a thing.

gemme.py

@@ -530,7 +530,7 @@ def doit(inAli,mutFile,retMet,bFile,fFile,n,N, jetfile, pdbfile, normWeightMode,
 
     #If a real pdb file is given, calculate dfi for the residues. 
     if(((normWeightMode=='dfi') or (normWeightMode=='max-trace-dfi') or (normWeightMode=='max-dfi-trace'))):
-        if (pdbfile != None):
+        if (pdbfile == None):
             print("ERROR: There is not any pdb file to calculate DFI.")
             sys.exit(-1)
         else:
@@ -549,7 +549,7 @@ def doit(inAli,mutFile,retMet,bFile,fFile,n,N, jetfile, pdbfile, normWeightMode,
     #If a real pdb file is given, calculate or get Bfactors for the residues. 
     if(((normWeightMode=='bfactor') or (normWeightMode=='max-trace-bfactor') or (normWeightMode=='max-bfactor-trace'))):
         isCalc = False
-        if (pdbfile != None):
+        if (pdbfile == None):
             print("ERROR: There is not any pdb file to calculate or get Bfactors!")
             sys.exit(-1)
         else: