#12 INTEGER conversion from and to integers of explicit sizes

[J-F Smigielski]

This patch allows the conversion of C integers, signed or unsigned, for integers of 8, 16, 32, 64 bits.

In facts, it is a simple generalisation of the work already made on "long integers" in the 0.9.21 version.

[J-F Smigielski]

Patch to skeleton files INTEGER.{h,c}

[J-F Smigielski]

Is it possible to have any feedback about this topic, please?

I admit this is not a main feature, but it helps having explicit code with fixed size integers.

[Lev Walkin]

Many platforms don't have 64-bit integers. So this patch will break more stuff than it fixes.