cli/daemon/dash/dashapp: fix base64 encoding of unicode (encoredev#97)

Fixes encoredev#96

cli/daemon/dash/dashapp: reset method on RPC change

Fixes encoredev#74

compiler: fix raw endpoints with path params

Add an end-to-end test for all variations to catch future regressions.

Update README.md

Update Slack channel link.

cli/daemon/dash/dashapp: fix trace rendering on auth error

If the auth handler reported an error the trace would be missing
the root request, causing an exception. Properly handle this case.

compiler: update encore.dev/beta/errs interface

To match new draft design.

compiler: initial implementation of encore.dev/beta/errs

This adds support for structured error handling in Encore.

For encoredev#19

Merge pull request encoredev#15 from encoredev/trace-logs

all: add request logs to traces

Merge pull request encoredev#15 from encoredev/trace-logs

all: add request logs to traces

README: update gopher logo