Implement overloaded not_before() and not_after().
Implement overloaded not_before() and not_after().

not_before() and not_after() are now functions, instead of strings.

If given a string as a argument they will perform an exact match against all
certificates using ASN1_TIME_print() as before. If given an integer they will
call X509_cmp_time() to compare against all values.

When given an integer not_before() will return true if the timestamp in the
integer is equal to or later than the notBefore attribute of any of the
certificates.

When given an integer not_after() will return true if the timestamp is
"before" (not inclusive) the notAfter attribute of any of the certificates.

There is still a problem with functions in an array of structures if not
scanning a PE file. I still have to debug that.

beikezcs/yara,binsrc/yara,tanium/yara,tdr130/yara,MeteorAdminz/yara,jshufelt/yara,hillu/yara,cblichmann/yara,jshufelt/yara,mgoffin/yara,jpypi/yara,tanium/yara,MeteorAdminz/yara,Security513/yara,pombredanne/yara,smaudet/yara,rednaga/yara,wxsBSD/yara,neatsun/yara,kallanreed/yara,cblichmann/yara,rayyang2000/yara,digideskio/yara,frbapolkosnik/yara,kallanreed/yara,jshufelt/yara,digideskio/yara,VirusTotal/yara,tdr130/yara,foreni-packages/yara,mgoffin/yara,0x0mar/yara,msuvajac/yara,pombredanne/yara,smaudet/yara,tdr130/yara,smaudet/yara,pombredanne/yara,bmagistro/yara,VirusTotal/yara,msuvajac/yara,plusvic/yara,neatsun/yara,neatsun/yara,Security513/yara,hillu/yara,binsrc/yara,wxsBSD/yara,wxsBSD/yara,0x0mar/yara,Security513/yara,msuvajac/yara,bmagistro/yara,bmagistro/yara,rayyang2000/yara,jshufelt/yara,0x0mar/yara,plusvic/yara,VirusTotal/yara,plusvic/yara,VirusTotal/yara,MeteorAdminz/yara,binsrc/yara,digideskio/yara,plusvic/yara,mgoffin/yara,wxsBSD/yara,rednaga/yara,foreni-packages/yara,hillu/yara,hillu/yara,jpypi/yara,beikezcs/yara,rednaga/yara,0x0mar/yara,frbapolkosnik/yara,frbapolkosnik/yara,frbapolkosnik/yara,pombredanne/yara,binsrc/yara,smaudet/yara,mgoffin/yara,cblichmann/yara,plusvic/yara,foreni-packages/yara,jpypi/yara,hillu/yara,cblichmann/yara,VirusTotal/yara,pombredanne/yara,beikezcs/yara,digideskio/yara,kallanreed/yara,rayyang2000/yara,tanium/yara,cblichmann/yara,wxsBSD/yara