Rename task_get_free_fhandle
Use global FILEINFO
Use global disk image
Use FAT image directly
Change `file_delete` function to receive filename
Fix API_DELETE
Add `file_open` function
Remove `file_loadfile` function
Change `file_create` to `file_writeopen`

And receive FILEHANDLE to store file information.
Create .hrb file header struct
Read program data into data area directly

to reduce memory consuption.
Remove unimportant files from disk image