comments_corp updated for new column names

'user' and 'track' updated to 'user_id' and 'track_id' in favesp()
function within comments_corp.py
Merge branch 'master' of https://github.com/ValuingElectronicMusic/network-analysis
bug fixes for get_minimal_lomem

removed the results of some careless cut-and-pasting
ongoing work with detect_english

now using most common 5k words in british national corpus instead of
OpenOffice spelling dictionaries (faster - and less liable to be
confused by e.g. Italian loanwords)
Added .txt files to gitignore

Can undo this later. Should change the module that's producing them to
produce e.g. .tmp instead.