Module utils

Reads the file, tokenizes the each line with delimiter, and returns the
dict.
It ignores the lines which start with '#'.

@type filename: string
@param filename: The name of the input file.

@type delimiter: string
@param delimiter: line is divided from delimiter to create the
    <key,value> of dict.

@type pat_replace: dict
@param pat_replace: this dict can be used to replace pattern, if specified.
    For example: pat_replace={'#.*':'', '\s+':' '} would do...
        - replace all characters starting from '#' to end of the line
          with '' and
        - replace multiple spaces with one space.

@type ignore_case: bool
@param ignore_case: it is used to create the lowercase keys to make case
    insensitive search

-------------
Illustration:
-------------
    A call to get_spec_dict(filename, pat_replace={'#.*':'', '\s+':' '})
    with following file..
    file content = "
         #CombGen input file

         #Core molecule
         Core: cg_singledock_run1_tproj38171a23586-core.mae

         #Attachment AcCl
         Chain: AcCl 1 1 1f 1t
         Frag: AcCl 1 cg_acid_chlorides_Acid_Cl_C_C

         #Attachment Hyd
         Chain: Hyd 1 1 2f 2t
         Frag: Hyd 1 cg_hydrazines_Hydrazine_C_N

         #Attachment NCO
         Chain: NCO 1 1 3f 3t
         Frag: NCO 1 cg_isocyanates_Isocyanate_C_N
    "
    would return spec_dict as follow...
    {'frag': ['AcCl', '1', 'cg_acid_chlorides_Acid_Cl_C_C',
             'Hyd', '1', 'cg_hydrazines_Hydrazine_C_N',
             'NCO', '1', 'cg_isocyanates_Isocyanate_C_N'],
     'core': ['cg_singledock_run1_tproj38171a23586-core.mae'],
     'chain': ['AcCl', '1', '1', '1f', '1t',
               'Hyd', '1', '1', '2f', '2t',
               'NCO', '1', '1', '3f', '3t']}