The PureEvaler abstraction made things unnecessarily complex; it's better to
just create a real Evaler for tests is pretty.
The Evaler has a new ReplaceBuiltin method to make it easier to construct the
expected test result.
Instead of putting all possible flags in prog.Flags, flags are now registered by
the individual subprograms. The 3 flags -sock, -db and -json are shared by
multiple subprograms and still handled by the prog package.
This new design allows separating the support for -cpuprofile into a separate
subprogram, which is no longer included by the default entry point, making the
binary slightly smaller. A new entrypoint "withpprof" is created.
Also include the LSP subprogram in the nodaemon entry point.
