Fix POM, update package name a bit, update NXDT-related part

src/main/java/nsusbloader/Utilities/nxdumptool/NxdtNspFile.java

@@ -0,0 +1,67 @@
+/*
+    Copyright 2019-2020 Dmitry Isaenko, DarkMatterCore
+
+    This file is part of NS-USBloader.
+
+    NS-USBloader is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    NS-USBloader is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with NS-USBloader.  If not, see <https://www.gnu.org/licenses/>.
+*/
+package nsusbloader.Utilities.nxdumptool;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+public class NxdtNspFile {
+    private final String name;
+    private final int headerSize;
+    private final long fullSize;
+    private long nspRemainingSize;
+    private final File file;
+
+    NxdtNspFile(String name, int headerSize, long fullSize, File file) throws Exception{
+        this.name = name;
+        this.headerSize = headerSize;
+        this.fullSize = fullSize;
+        this.file = file;
+        this.nspRemainingSize = fullSize - headerSize;
+
+        removeIfExists();
+        createHeaderFiller();
+    }
+    private void removeIfExists() throws Exception{
+        if (! file.exists())
+            return;
+
+        if (file.delete())
+            return;
+
+        throw new Exception("Unable to delete leftovers of the NSP file: "+name);
+    }
+    private void createHeaderFiller() throws Exception {
+        try (RandomAccessFile raf = new RandomAccessFile(file, "rw")){
+            raf.setLength(headerSize);
+        }
+        catch (IOException e){
+            throw new Exception("Unable to reserve space for NSP file's header: "+e.getMessage());
+        }
+    }
+
+    public String getName() { return name; }
+    public int getHeaderSize() { return headerSize; }
+    public long getFullSize() { return fullSize; }
+    public File getFile() { return file; }
+    public long getNspRemainingSize() { return nspRemainingSize; }
+
+    public void setNspRemainingSize(long nspRemainingSize) { this.nspRemainingSize = nspRemainingSize; }
+}