Added initial version of a Linux build-script

build-linux.sh is meant to use FPC on Linux only.

Support for FPC on Windows will have to come at a later time, if at
all.
Moved integer-type size-check to a function

FPC complained about unreachable code because it noticed that all the
integer-types declared in GlobalTypes.pas were the correct size, and
therefor the error-message would never be displayed.

I moved the size-check into a separate function to trick FPC into
not seeing that at compile-time.
Reorganized the FPC/Linux build-script
Added *.o and *.ppu to .gitignore

These are output-files generated by FPC.
Another workaround for FPC unreachable-code-error
Bugfix: PrepareRobot /cleardb only handles DbNr=0

This is VERY minor. A line of code was commented-out, which caused
only the first database-shard to be handled in the ClearDb feature.

I haven't used this feature in years, and there is barely a use-case
for it anymore, so the entire feature could probably be removed.

But for now I just fixed the bug. :)
Changed the build-order of several files

Moved the files that don't compile yet with FPC on Linux to the
end of the list.
Commented-out a line of code to make GenDb compile

FPC is more picky than Delphi. :)

That line of code only printed a value in the very, VERY
unlikely event of an internal error. And that value isn't
really important anyway. So just don't show it.
Merge pull request #1 from MichaelSchoebel/fpc-linux

Some preparatory work to get everything to compile with FPC on Linux