fixed subsystems according to specification

1) filled gaps between 
IMAGE_SUBSYSTEM_WINDOWS_CUI = 3
and
IMAGE_SUBSYSTEM_POSIX_CUI = 7 (not 4!),
and 
IMAGE_SUBSYSTEM_WINDOWS_CE_GUI = 9 (not 5!)
2) fixed total amount of subsystems from 10 to 14
Merge pull request #52 from TrueBers/patch-1

fixed subsystems according to specification
Makefile: Fix srcdir.
Adapt pepack for the new libpe.
pescan: Attempt to get rid of global variables.
Remove unnecessary header files.
Transplant README from master.
Update README.
Adapt pestr for the new libpe.
Adapt pedis for the new libpe.
Adapt peres for the new libpe.
pedis: Use the new pe_load_ext to load the binary file and keep its
stream open for further usage. It's not being used right now, but I
kept it as an example for others.
Update libpe reference.
peres: Fix possible memory leaks introduced by 518d39b.
merging mmap branch
Update libpe.
changing libpe submodule reference to master branch
minor 0.70 updates
adding info about the new peres tool
fixed bug header name handling