made browser cash browser class field. better.
some syntax stuff fixed.

weird error in page rank method when called from browser:
8, in <dictcomp>
 reg = {t:score(t)+dist(t) for t in blgs}
File "/media/Data/Codes/Python/python-misc/tumblr/weave/tumblr.py", line 300, in <lambda>
 score = lambda t: reg.get(t,0)/2 + img_score(t) / (1+len(t.images)/100)