volume: Various asked changes (math trickery/style/bug)
volume: Various asked changes (math trickery/style/bug)

	* Use replacement trickery to remove leading minus sign
	* Squash down the size of one switch case
	* Issue would happen with volume down "".
	* Refactored error/help 1>&2
	* Now checks integer-ish-ness in relative_volume

dnschneid/crouton,ikaritw/crouton,tonyxue/cruise,rperce/chroagh,StrawnPoint04/crouton,taterbase/crouton,fxcebx/crouton,dnschneid/crouton,dnschneid/crouton,djmrr/crouton,nromsdahl/crouton,tonyxue/cruise,twmccart/crouton,stephen-soltesz/crouton,mkasick/crouton,jamgregory/crouton,dnschneid/crouton,taterbase/crouton,elkangaroo/chroagh,ikaritw/crouton,fxcebx/crouton,DanDanBu/crouton,DanDanBu/crouton,stephen-soltesz/crouton,ikaritw/crouton,nromsdahl/crouton,DanDanBu/crouton,arbuztw/crouton,djmrr/crouton,fxcebx/crouton,tonyxue/cruise,stephen-soltesz/crouton,ikaritw/crouton,zofuthan/crouton,stephen-soltesz/crouton,dnschneid/crouton,rperce/chroagh,taterbase/crouton,jamgregory/crouton,taterbase/crouton,brayniac/crouton,mkasick/crouton,StrawnPoint04/crouton,mkasick/crouton,arbuztw/crouton,tonyxue/cruise,djmrr/crouton,mkasick/crouton,stephen-soltesz/crouton,jamgregory/crouton,brayniac/crouton,VandeurenGlenn/crouton,arbuztw/crouton,djmrr/crouton,nromsdahl/crouton,nromsdahl/crouton,VandeurenGlenn/crouton,rperce/chroagh,twmccart/crouton,tonyxue/cruise,elkangaroo/chroagh,StrawnPoint04/crouton,DanDanBu/crouton,twmccart/crouton,jamgregory/crouton,zofuthan/crouton,DanDanBu/crouton,rperce/chroagh,zofuthan/crouton,nromsdahl/crouton,StrawnPoint04/crouton,VandeurenGlenn/crouton,fxcebx/crouton,StrawnPoint04/crouton,arbuztw/crouton,elkangaroo/chroagh,twmccart/crouton,djmrr/crouton,StrawnPoint04/crouton,taterbase/crouton,DanDanBu/crouton,twmccart/crouton,elkangaroo/chroagh,elkangaroo/chroagh,brayniac/crouton,arbuztw/crouton,mkasick/crouton,rperce/chroagh,ikaritw/crouton,mkasick/crouton,stephen-soltesz/crouton,brayniac/crouton,ikaritw/crouton,nromsdahl/crouton,VandeurenGlenn/crouton,fxcebx/crouton,twmccart/crouton,arbuztw/crouton,djmrr/crouton,zofuthan/crouton,rperce/chroagh,taterbase/crouton,jamgregory/crouton,fxcebx/crouton,elkangaroo/chroagh,tonyxue/cruise,VandeurenGlenn/crouton,brayniac/crouton,zofuthan/crouton,jamgregory/crouton,zofuthan/crouton,brayniac/crouton,dnschneid/crouton,VandeurenGlenn/crouton