Tracer code to query multiple pages

Relies entirely on the ‘start’ URL parameter.  For the sake of this
experiment, I’m looping through 4 pages of 20 results each before
quitting.  This is done by using the same query object multiple times,
just setting the start index to the new value with each iteration.
Looping until the end of the search is reached
Limiting multi-page searches

The max number of results to be returned will either be +inf or the max
number of search results provided by the user.
Using ScholarConf.MAX_PAGE_RESULTS
Renaming 'start' to 'start_index'
I added the option to search articles that cite a given cluster id. It seems to work fine.
In addition to the key "&cites", I also had to put the key/value "&scipsc=1". As I do not know was the second key means, it is only added for "cites" searches.
Merge branch 'pulls/21'
Merge branch 'pulls/11'

Conflicts:
	scholar.py