Project restructure (no new code added)

Moved all header files into include/ and removed their C counterparts -> code inside .h files
Also added a kernel.ld linker file
since we don't have many code files in src/ now, i removed src/kernel/
only real code change is that i moved memcopy() and memset() into string.h from system.h

kernel.ld

@@ -0,0 +1,14 @@
+SECTIONS {
+    .text 0x1000 : {
+        *(.text*);
+    }
+    .data : {
+        *(.data*);
+    }
+    .rodata : {
+        *(.rodata*);
+    }
+    .bss : {
+        *(.bss*);
+    }
+}