Issues with matching of Hollerith constants

[reuterbal]

Sorry, another archaic one... Matching of Hollerith constants seems to have a few issues. I noticed the following:

1. In a Format string, if the last item before the closing parenthesis is a Hollerith constant that ends in a white space, parsing fails (which might be a strip() or rstrip() issue?). The actual NoMatchError might be connected to 2. below.

   
   >>> from fparser.two.parser import ParserFactory
   >>> parser = ParserFactory().create()
   >>> from fparser.api import get_reader
   >>> fcode = 'PROGRAM HOLLERITH\n901 FORMAT (2HA ,1X)\nEND PROGRAM HOLLERITH'
   >>> parser(get_reader(fcode))
   Program(Main_Program(Program_Stmt('PROGRAM', Name('HOLLERITH')), Specification_Part(Implicit_Part(Format_Stmt('FORMAT', Format_Specification('(', Format_Item_List(',', (Hollerith_Item('A '), Position_Edit_Desc(Digit_String('1', None), 'X'))), ')')))), End_Program_Stmt('PROGRAM', Name('HOLLERITH'))))
   >>> fcode = 'PROGRAM HOLLERITH\n901 FORMAT (2HA )\nEND PROGRAM HOLLERITH'
   >>> parser(get_reader(fcode))
   Traceback (most recent call last):
   File "/.../src/fparser/two/Fortran2003.py", line 237, in __new__
   return Base.__new__(cls, string)
   File "/.../src/fparser/two/utils.py", line 407, in __new__
   raise NoMatchError(errmsg)
   fparser.two.utils.NoMatchError: at line 2
   >>>901 FORMAT (2HA )

During handling of the above exception, another exception occurred:

Traceback (most recent call last): File "", line 1, in File "/.../src/fparser/two/Fortran2003.py", line 241, in new raise FortranSyntaxError(string, "") fparser.two.utils.FortranSyntaxError: at line 2

901 FORMAT (2HA )

2. If the character count does not match the number of following characters, it fails to match. The webpage [linked to](https://gcc.gnu.org/onlinedocs/gfortran/Hollerith-constants-support.html) from the documentation however states that in such cases the constant is truncated or padded:
```python
>>> fcode = 'PROGRAM HOLLERITH\n901 FORMAT (2HAAA ,1X)\nEND PROGRAM HOLLERITH'
>>> parser(get_reader(fcode))
Traceback (most recent call last):
  File "/.../src/fparser/two/Fortran2003.py", line 237, in __new__
    return Base.__new__(cls, string)
  File "/.../src/fparser/two/utils.py", line 407, in __new__
    raise NoMatchError(errmsg)
fparser.two.utils.NoMatchError: at line 2
>>>901 FORMAT (2HAAA ,1X)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/.../src/fparser/two/Fortran2003.py", line 241, in __new__
    raise FortranSyntaxError(string, "")
fparser.two.utils.FortranSyntaxError: at line 2
>>>901 FORMAT (2HAAA ,1X)

[reuterbal]

Digging out a very old issue, just to point out that case 1 above works now correctly:

 python3 -c "
from fparser.two.parser import ParserFactory; from fparser.api import get_reader; parser = ParserFactory().create(); fcode = 'PROGRAM HOLLERITH\n901 FORMAT (2HA )\nEND PROGRAM HOLLERITH'; print(parser(get_reader(fcode)))"
PROGRAM HOLLERITH
901 FORMAT(2HA )
END PROGRAM HOLLERITH

However, case 2 is not handled in the expected way, yet:

 python3 -c "
from fparser.two.parser import ParserFactory; from fparser.api import get_reader; parser = ParserFactory().create(); fcode = 'PROGRAM HOLLERITH\n901 FORMAT (2HAAA ,1X)\nEND PROGRAM HOLLERITH'; print(parser(get_reader(fcode)))"
Traceback (most recent call last):
  File "/etc/ecmwf/nfs/dh1_home_a/nabr/loki/main/loki_env/lib/python3.8/site-packages/fparser/two/Fortran2003.py", line 267, in __new__
    return Base.__new__(cls, string)
  File "/etc/ecmwf/nfs/dh1_home_a/nabr/loki/main/loki_env/lib/python3.8/site-packages/fparser/two/utils.py", line 501, in __new__
    raise NoMatchError(errmsg)
fparser.two.utils.NoMatchError: at line 2
>>>901 FORMAT (2HAAA ,1X)