FragmentCollection: methods next(), prev(), bind Lua + test
remove struct FragmentDiff and methods using it
FragmentCollection: neighboring methods, Lua, test

 * neighbor(f, ori)
 * logical_neighbor(f, ori)
 * int are_neighbors(f1, f2)
 * another_neighbor(f1, f2)
FragmentCollection<vector>: shrink vector on remove

.remove() seemed not to work properly on vector variant
of FragmentCollection.
add number of common typedef for variants of FragmentCollection
remove OneByOne
Joiner: update class decription
FragmentCollection: add methods .seqs() and .fragments_of()
move FragmentCollection from algo/ to model/

--HG--
rename : src/algo/FragmentCollection.hpp => src/model/FragmentCollection.hpp
mark FragmentCollection.another_neighbor const
Sequence.circular() doesn't throw
FragmentCollection: add method .has_seq()
shorten long line
Rest: use FragmentCollection instead of prev/next
test-lua/fragment.lua: fix memory leak
TrySmth: use Align instead of ReAlign
TrySmth: add ReAlign before Align and test for this
Fragment, Block: remove nonused methods exclude and split
Fragment, Block: remove shifting methods