change the structure of fragment linkers
implement the equals function on CRD
implement a function to detect 1 by 1 fragment pairs
[bug fix]
implement a function to judge whether the given two blocks satisfy conditions to be linked
make fragment linker use the umpire
add a field to CodeFragmentInfo that represents hash value calculated from non-normalized string
create an abstract class to retrieve elements from db
create a class for retrieving revisions
create an abstract class for retrieving elements that exist across multiple revisions
create an abstract class for retrieving linked elements
create a class for retrieving files
create a class for retrieving code fragments
create an abstract class for retrieving volatile elements
create a class for retrieving clone sets
create a class for retrieving links of code fragments
create a class for retrieving links of clone sets
[refactoring] move package
create a class for retrieving clone genealogies
create a class for retrieving crds