Moved some lines and deleted old code

* Removed Compiler ELF references from rpcs3.cpp
* Reordered the menu bar lines.
* Moved the construction of some panels of MainFrame from rpcs3.cpp to
MainFrame.cpp
PKG Loader rewritten

* Rewritten unpkg.c -> Loader/PKG.cpp
* MainFrame::InstallPkg now *only* installs the PKG.
* Fixed crash when unpacking big debug PKG files.
* Debug PKGs are no longer recrypted.
* 'About...' dialog updated to remove PKG-related notice.
* Unpkg removed.

NOTE: The class PKGLoader is using wxWidgets functions to access the
files. I think VFS would be better, but the Emulator isn't necessarily
running when installing the PKG. In the other hand, initializing VFS
with RPCS3 may be somewhat risky... Any alternatives?

TODO: Get rid of the decrypted "*.dec" files, and try to decrypt and
read contents of the PKG on the fly using the information stored in
m_entries.