clean headings

gotye/somebody_that_i_used_to_know.sg

 \selectlanguage{english}
 \songcolumns{1}
 \beginsong{Somebody that I used to know}
-  [by=Gotye,cov=making-mirrors,album=Making Mirrors]
+  [by={Gotye},cov={making-mirrors},album={Making Mirrors}]
 
   \cover
   \gtab{Dm}{5:X02210}

noir_desir/the_holy_economic_war.sg

 \selectlanguage{english}
 \songcolumns{1}
 \beginsong{The holy economic war}
-  [by=Noir Désir,cov=du-ciment-sous-les-plaines,album=Du ciment sous les plaines]
+  [by={Noir Désir},cov={du-ciment-sous-les-plaines},album={Du ciment sous les plaines}]
 
   \cover
   \gtab{C}{X32010}

pink_floyd/mother.sg

 \selectlanguage{english}
 \songcolumns{1}
 \beginsong{Mother}
-  [by=Pink Floyd,cov=the-wall,album=The Wall]
+  [by={Pink Floyd},cov={the-wall},album={The Wall}]
 
   \cover
   \gtab{G}{320003}

the_kingston_trio/greenback_dollar.sg

 \selectlanguage{english}
 \songcolumns{1}
 \beginsong{Greenback Dollar}
-  [by=The Kingston Trio,cov=new-frontier,album=New Frontier]
+  [by={The Kingston Trio},cov={new-frontier},album={New Frontier}]
 
   \cover
   \gtab{Em}{022000}

the_rolling_stones/gimme_shelter.sg

 \selectlanguage{english}
 \songcolumns{2}
 \beginsong{Gimme shelter}
-  [by=The Rolling Stones,cov=let-it-bleed,album=Let it bleed]
+  [by={The Rolling Stones},cov={let-it-bleed},album={Let it bleed}]
 
   \cover
   \capo{2}