merge hex_split.py and makehex.py

[jjts]

and make a python module to import and not to run standalone

[jjts]

These should be integrated into py2 and called memory modules

hex_split should be called by tiled memories

A good project is to have a memory generation tool that generates all the memory types under the folder lib/hardware/modules/mem

may work together with @mbot27

[arturum1]

The hex_split.py and makehex.py are called by makefiles in the build directory, so they should support running as standalone.
They are used to create the .hex files of the bootloader and firmware, to load them into system memories.

I can merge the hex_split.py script into the makehex.py one. In this case, calling the makehex.py would generate all the .hex files: the complete one with 4 byte words; and the other ones that contain 1 byte words each.

[jjts]

makehex.py --split (default no split)

call it with --split , same as hex_split

call it without--split, same as old makehex