Restructured Code

* Move layer info struct and associated functions to dedicated c/h files.
* Rename layer selector folder more generic "layer"

Besides from restructuring nothing changes

latex-output/latex-output.h

@@ -34,7 +34,7 @@
 #include "../gds-parser/gds-types.h"
 #include <glib.h>
 #include <stdio.h>
-#include "../mapping-parser.h"
+#include "../layer/layer-info.h"
 
 #define LATEX_LINE_BUFFER_KB (10) /**< @brief Buffer for LaTeX Code line in KiB */