Code improvements

[davy7125]

Hi,

Several non-critical things:

• the following dependencies could be avoided if you remove non essential functions: xml module of Qt, libsndfile,
• C++11 could be avoided by rewriting the initialization of a structure,
• warnings could be removed (memset(&p, sizeof(p), 0); / unused variables),
• a namespace is missing,
• readCompressedSample is dead code.