"Modify" for non-string values

Added the possibility to modify float, integer e bool values (using explicitly true/false)
Changing to some more meaningful names
Print number of tracks on disc to simplify the decision of switching to singleton mode
version bump: 1.1.1
Merge pull request #267 from jayme-github/album_itemcount

Print number of tracks when importing
rewrap and changelog note for #267
Merge pull request #265 from duailibe/modify

"Modify" for non-string values
move type conversion to commands module (#265)

This change also uses the existing str2bool utility function.
changelog/thanks for #265
Merge pull request #261 from mschuerig/master

Support for year queries with ranges