Add is_dll(), is_3bit() and is_64bit() to pe.
Add is_dll(), is_3bit() and is_64bit() to pe.

I've fielded questions from a handful of people on how to do this and while it
is easy it could be easier if we just provided some convenience functions to do
this.

Security513/yara,VirusTotal/yara,cblichmann/yara,tanium/yara,MeteorAdminz/yara,hillu/yara,pombredanne/yara,wxsBSD/yara,tanium/yara,msuvajac/yara,MeteorAdminz/yara,pombredanne/yara,hillu/yara,rednaga/yara,hillu/yara,jpypi/yara,pombredanne/yara,tanium/yara,hillu/yara,bmagistro/yara,hillu/yara,rednaga/yara,mgoffin/yara,jpypi/yara,msuvajac/yara,wxsBSD/yara,cblichmann/yara,msuvajac/yara,cblichmann/yara,wxsBSD/yara,mgoffin/yara,kallanreed/yara,Security513/yara,VirusTotal/yara,plusvic/yara,VirusTotal/yara,pombredanne/yara,jpypi/yara,wxsBSD/yara,VirusTotal/yara,kallanreed/yara,bmagistro/yara,kallanreed/yara,Security513/yara,wxsBSD/yara,cblichmann/yara,VirusTotal/yara,plusvic/yara,cblichmann/yara,bmagistro/yara,MeteorAdminz/yara,plusvic/yara,plusvic/yara,rednaga/yara,pombredanne/yara,plusvic/yara,mgoffin/yara,mgoffin/yara