Fix Makefile typo
Add orphan tags to non-default docbuild targets

The orphan tag suppresses Sphinx's complaints about their exclusion from certain docbuild targets
Make doctests pass

Reflects lots of small changes in printouts and error messages, line numbers, etc.

Nontrivial changes:
- Bump JuliaDoc submodule
- The control flow documentation had to be reformatted slightly to make
  doctests pass.  The output of Task(...) now prints out a memory
  address which is clearly not reproducible, so the output is
  suppressed.
- Some roundoff printing issues in complex-and-rational-numbers?
- isequal(NaN,NaN32) == true
- It also looks like sqrt(-1) no longer prints a helpful error message
  about trying sqrt(complex(-1))...?
- strings.rst, line 239: "ERROR: BoundsError() in getindex at
  ascii.jl:11" no longer prints out traceback??
- control-flow.rst, line 638: UndefVarError->MyUndefVarError to prevent
  overwriting Base UndefVarError

WARNNG: Because union types appear to be unsorted on output, sometimes
Union(a,b) is printed out as Union(b,a). This causes the doctests to
fail nondeterministically, e.g.

Failed example:
    super(Union(Float64,Int64))
Expected:
    ERROR: `super` has no method matching super(::Type{Union(Float64,Int64)})
Got:
    ERROR: `super` has no method matching super(::Type{Union(Int64,Float64)})