is_code_ref can now be an opcode too
reimplement run_code in terms of render_string
turned render_string into an opcode
reimplement new_vars_for in terms of merge_hash
merge_hash is now an opcode
don't constant-fold render_string
avoid calling find_file multiple times
simplify
move most of find_file into the compiler
simplify the logic for template suffixes

now, anything that doesn't contain a '.' will have the suffix appended
unconditionally, rather than looking for both the suffixed and
unsuffixed versions. this is more in line with how text::xslate
typically works.
find_file and suffix are now opcodes
add test for loading just the syntax on its own
gfx doesn't want to support a render_string opcode
depend on newer xslate
fix .. in block helpers