#2 Flexible build of internal lookup-up table

[Remi Chateauneu]

This library contains an internal lookup table made of 10000 decimal numbers of four digits, counting from 0000 to 9999. At the moment, this table is statically built.

It might be interesting to give some flexibility to the way this table is built:
- to reduce code size
- to control where it is allocated (ROM is slower than RAM).

Therefore, it would be nice to provide two choices:
- To provide this big table in an optional source file, with a unique external symbol, the beginning of the table.
- And, optionaly, provide a function building this table in any block of 40000 bytes, which would be called at program startup.