Issue 37

[jferard]

I summarize what issue 37 is. When reading a Memo file, the current code tries to emulate a random access with the following method:

• mark the stream (8192 bytes) once
• for each read:
  • reset the stream
  • skip n bytes
  • read k bytes.

This method is fragile:

• the mark may be insufficient
• "InputStream.skip() method may skip fewer bytes than requested" (pointed by wescleveland56)

We need a real random access, but with a low memory footprint (= without loading the whole file in memory: see issue #5 and commit d99575c) and with a good speed. This PR proposes to use a MappedByteBuffer (see https://www.codeproject.com/Tips/683614/10-Things-to-Know-about-Memory-Mapped-File-in-Java) to let the OS deal with the disk accesses, rather than a plain RandomAccessFile.

Note 1: no speed tests made.
Note 2: I updated .gitignore to remove noise from Eclipse or Intellij...