tailor analyzers for files to match the structure change in previous commits
implement a function to retrieve methods from db
remove retrieveInSpecifiedRevision from AbstractElementRetriever
remove an unused method from AbstractElementRetriever.java
implement a function to retrieve vector data
change registerers to set the field of db connection with the specified instances
change retrievers to set the field of db connection with the specified instances
make DBConnection have registerers and retrievers as its field members
implement a function to update end revision ids
implement a function to retrieve methods in specified files
implement a function to analyze a specified revision
implement the main function of MethodAnalyzer
import some lacked libraries
[BUG_FIX] a bug was fixed that causes wrong cast when else statement was not a block
[BUG_FIX] a bug in MehtodDataRegisterer was fixed
create classes to manage printing messages
insert instructions for printing current states of processing