BC_ExcelAdmin.pm:
1. Refactor the flow in Class attributes subroutine, to be more clear
and reasonable.
2. Now we can change range for the same instance.
   Originally, you can't change the range of an instance once you set
it.
3. Now range() can provide more calling format, I appended:
   range(sheet_index)
   range(sheet_index, r_start_number) -- start from row r, all columns
   range(sheet_index, c_start_number) -- start from col c, all rows
   range(sheet_index, r_start_number, c_start_number) -- start from row
r and col c, all left
4. Fix bug:
   I forgot to check $href in sub:
   _format_table
   _format_table_with_header_and_index
   _format_table_with_header_but_no_index

BC_Math.pm:
1. Add judge for range_check().

BC_NetworkAdmin.pm
1. Refactor the flow in Class attributes subroutine, to be more clear
and reasonable.

BC_Term_Menus.pm
1. Just add as initial version without any use.