get_lib_cells

Get leaf gates in libraries 
Usage: my @cells = get_lib_cells($pattern, @options);
@options:
     -help:            This information
     -char:            All cells characterization
     -type leaf_type:  Get leaf gates matching type. 
                       Leaf_type can be 'ff', 'latch', 'cg', 'buf', 'not', 'and' ...
     -type_info:       List all types in the current loaded libraries
     -verbose:         If $pattern matches only one lib cell, print the cell lib information
$pattern: Library cell name pattern, can have '*'.
@cells: Return array with name matching