Added buffer plus verbose option

Motivation (performance impovement)

time python wordlist.py '[a-z]' -m 1 -M 4 -o file  -v

Progress: ==================== 100%
wordlist.py List size: 2357264 bytes

Time 2.82s user 0.52s system 94% cpu 3.514 total

time python wordlist.py '[a-z]' -m 1 -M 4 -o file

wordlist.py List size: 2357264 bytes
Time 0.57s user 0.02s system 96% cpu 0.605 total