Cleaned up some cases where resolver errors produced distracting backtraces during compilation: Use low_cast_to_(object|program) in dirnode instead of the variants that throw errors. Added compile_cb_error and compile_cb_rethrow to be able to throw errors that are converted to plain compiler error messages. Fixed describe_backtrace and describe_error to use more convenient ways for getting the messages and backtraces out if error objects, so that the ugly overloading of `[] isn't necessary. Added get_backtrace to get the backtrace out of an error array/object, just like describe_error gets the error message. Cleaned up calls to compile_warning. Fixed error propagation from decode_charset. Shortened accesses to _static_modules.Builtin and _static_modules.___files. Rev: lib/master.pike.in:1.310