WIP: Moved sources int src/, separated most of the source code from Perl.

The XS was left only for the unit / integration tests, and it links
libslic3r only. No wxWidgets are allowed to be used from Perl starting
from now.

src/png/zlib/contrib/iostream2/zstream_test.cpp

@@ -0,0 +1,25 @@
+#include "zstream.h"
+#include <math.h>
+#include <stdlib.h>
+#include <iomanip.h>
+
+void main() {
+    char h[256] = "Hello";
+    char* g = "Goodbye";
+    ozstream out("temp.gz");
+    out < "This works well" < h < g;
+    out.close();
+
+    izstream in("temp.gz"); // read it back
+    char *x = read_string(in), *y = new char[256], z[256];
+    in > y > z;
+    in.close();
+    cout << x << endl << y << endl << z << endl;
+
+    out.open("temp.gz"); // try ascii output; zcat temp.gz to see the results
+    out << setw(50) << setfill('#') << setprecision(20) << x << endl << y << endl << z << endl;
+    out << z << endl << y << endl << x << endl;
+    out << 1.1234567890123456789 << endl;
+
+    delete[] x; delete[] y;
+}