added the ability to split tags, inverse of the tag merge functionality
remove unused function
fix formatting
Merge branch 'TagSplit' of https://github.com/jcwmoore/ampache into jcwmoore-TagSplit
changes suggested by @SUTJael
Fix artist past events list
Allow artist description edit
Display place and year formed
remove tag splitting and change the tag merge functionality to allow merging to multiple tags
UPNP fixes and optimization

1) optimization: _xxxChilds: slice whole items array BEFORE converting to output objects
2) fix with special chars in items title.
Some players stops after receiving some special chars.
Don't know which exactly char is wrong, replace all special chars to '-'
Image art on artists edition and index display preferences
Merge pull request #460 from SeregaPru/develop

UPNP fixes and optimization
Restore 'Update from tags' link on albums
added the ability to keep existing tag mappings
Merge branch 'TagSplit' of https://github.com/jcwmoore/ampache into jcwmoore-TagSplit
Change update revision
Merge branch 'jcwmoore-TagSplit' into develop

Conflicts:
	lib/class/update.class.php
Fix #464
Fix #466
Add ip address on Ampache login failure log (fix #470)
add curl to requirements as optional

Since I notices the installer checks for `curl` it might as well be listed as an optional requirement.
Remove not ascii character from TXXX id3v2 tags