Simplestring::AtoI()

Move PlatformSpecificAtoI() to SimpleString.
Copied it is -- but from cl2000 code. Would have to find out about the license.

I have seen an alternative in http://www.ethernut.de/api/strtol_8c_source.html.
Doesn't look like we can use it, license-wise. Although I think the more basic the code, the less of an issue it will be. You will notice the code is bulkier, less straight-forward.

How about rewriting this in our own way. We would include only what we need for whitespace, upper and lower case and set more entries in our table to zero. We remove all macros that we don't use. We also let the table start at zero, because we are not interested in -1. In the end, it would no longer be copied, and it would not contain any dead code, and we could expand it later if and as needed.