Update bankscreen.simba

Line 103:
Changed BANK_CHEST_BURTHORPE to BANK_CHEST_LUMBRIDGE because there is no longer a bankchest in Burthorpe but there has been one in Lumbridge since November 2012

Line 1876:
Changed BANK_CHEST_BURTHORPE to BANK_CHEST_LUMBRIDGE and changed the colors to the colors of the Lumbridge chest

Line 1995:
Changed BANK_CHEST_BURTHORPE to BANK_CHEST_LUMBRIDGE

Line 2016:
Changed BANK_CHEST_BURTHORPE to BANK_CHEST_LUMBRIDGE
Merge pull request #109 from BMWxi/patch-2

Update bankscreen.simba