Generating Polyominoes

https://www.reddit.com/r/dailyprogrammer/comments/398mtv/20150610_challenge_218_intermediate_generating/

Usage

4
# of results: 5
Pattern:
XX  
X   
X   
    

Pattern:
XX  
XX  
    
    

Pattern:
X   
XX  
X   
    

Pattern:
X   
X   
X   
X   

Pattern:
X   
XX  
 X  
    

6
# of results: 33
Pattern:
XXX   
XX    
X     
      
      
      

Pattern:
XX    
XX    
X     
X     
      
      

Pattern:
XX    
XX    
XX    
      
      
      

Pattern:
XX    
XXX   
X     
      
      
      

Pattern:
XXX   
X     
X     
X     
      
      

Pattern:
XXX   
X     
XX    
      
      
      

Pattern:
XX    
X     
XX    
X     
      
      

Pattern:
XX    
X     
X     
X     
X     
      

Pattern:
XX    
X     
X     
XX    
      
      

Pattern:
XX    
X     
XX    
 X    
      
      

Pattern:
XX    
XXX   
 X    
      
      
      

Pattern:
XX    
XX    
 XX   
      
      
      

Pattern:
X     
XX    
XX    
X     
      
      

Pattern:
X     
XXX   
X     
X     
      
      

Pattern:
X     
XX    
X     
X     
X     
      

Pattern:
X     
XX    
XX    
 X    
      
      

Pattern:
X X   
XXX   
X     
      
      
      

Pattern:
X     
XXXX  
X     
      
      
      

Pattern:
X     
X     
XX    
X     
X     
      

Pattern:
X     
X     
X     
X     
X     
X     

Pattern:
X     
X     
X     
XX    
 X    
      

Pattern:
X     
X     
XXX   
 X    
      
      

Pattern:
X     
X     
XX    
 X    
 X    
      

Pattern:
X     
X     
XX    
 XX   
      
      

Pattern:
X     
X     
XXX   
  X   
      
      

Pattern:
X     
XXX   
 X    
 X    
      
      

Pattern:
X X   
XXX   
 X    
      
      
      

Pattern:
X     
XXXX  
 X    
      
      
      

Pattern:
X     
XX    
 XX   
 X    
      
      

Pattern:
X     
XX    
 X    
 XX   
      
      

Pattern:
X     
XX    
 XX   
  X   
      
      

Pattern:
X     
XXXX  
  X   
      
      
      

Pattern:
X     
XXXX  
   X