Fix #1193: Regression: Invalid XHTML in shiny exception template when first line in stack frame is HTML. Adds test for this and other issues. Also refs #926, #1150 and #1152
Allow configuration of prefix for route generation through options, closes #1194
merge 2e9832e724197bd83b1eb2dfaf6c3d4184f8314f to fd6705120fd72435324e052fa3512cd2c103a635 (from 1.0)