Add Google-style docstrings and fix bugs in pg_cmd, pg_lock, pg_opt, …

[zaihuaji]

…pg_split

pg_cmd.py:

• Added docstrings to all methods and class
• Fixed unescaped dot in dsid regex (r'^(ds\d|\d)\d\d.\d$' -> r'....\d$')
• Fixed NoneType concatenation crash in get_dynamic_options when SYSERR is None

pg_lock.py:

• Added docstrings to all methods and class
• Fixed update_partition_lock: pid counter underflow (added max(0, ...))
• Fixed update_partition_lock: potential KeyError on missing 'pid' key
• Fixed update_partition_lock: inconsistent early-return value (0 -> None)
• Fixed lock_process_info: implicit None check -> explicit is not None

pg_opt.py:

• Added docstrings to all 40+ methods and class
• Fixed set_sudo_uid/set_root_uid: self.params['CACT'] -> self.PGOPT['CACT']
• Fixed set_sudo_uid/set_root_uid: missing closing quote in format strings
• Fixed set_option_value: str builtin used instead of local variable dstr
• Fixed validate_one_infile: == None -> is None
• Fixed get_control_frequency: wrong return value on error (returned unit char instead of error message string)
• Fixed append_format_string: unescaped regex metacharacters in fmt

pg_split.py:

• Added docstrings to all methods and class
• Fixed compare_wfile: [[]]*flen shallow copy bug (all fields shared one list)
• Fixed compare_wfile: dsrecs.keys() live view -> list(dsrecs.keys())