Add PhysicalConstants evaluation to @ufac_str

Now we have two sets of Physical constants accessible this way:
 Na,q,k etc. from Unitful (didn't see them before)
 N_A,e, k_B from PhysicalConstants.CODATA2018

The former are buggy under Julia 1.8, see
PainterQubits/Unitful.jl#545

Also, this taps now into the deeper mechanisms of Unitful. Look like a rabbit hole...

Project.toml

@@ -1,7 +1,7 @@
 name = "LessUnitful"
 uuid = "f29f6376-6e90-4d80-80c9-fb8ec61203d5"
 authors = ["Jürgen Fuhrmann <[email protected]>"]
-version = "0.4.0"
+version = "0.5.0"
 
 [deps]
 PhysicalConstants = "5ad8b20f-a522-5ce9-bfc9-ddf1d5bda6ab"

src/LessUnitful.jl

@@ -44,6 +44,14 @@ unitfactor(u) = unitfactor(Unitful,u)
 unitfactor(U::Module,u::Unitful.FreeUnits) = unitfactor(U,1u)
 unitfactor(U::Module,quantity) = U.float(U.ustrip(U.upreferred(quantity)))
 
+function _ufac_str(x)
+ Unitful=getproperty(@__MODULE__,:Unitful)
+ PhysicalConstants=getproperty(@__MODULE__,:PhysicalConstants)
+ code = Expr(:block)
+ push!(code.args, :(unitfactor($(Unitful),eval($(Unitful).lookup_units(($(PhysicalConstants).CODATA2018,$(Unitful)), Meta.parse($x))))))
+ code
+end
+
 """
  @ufac_str
 
@@ -54,14 +62,35 @@ String macro for calculating the unit factor of a quantity, see also [`unitfacto
 julia> ufac"1mV"
 0.001
 ```
+
+This macro allows as wellto obtatin unit factors from physical constants from [PhysicalConstants.CODATA2018](https://juliaphysics.github.io/PhysicalConstants.jl/stable/constants/#CODATA2018-1)
+
+```jldoctest
+julia> ufac"N_A"
+6.02214076e23
+```
+
+```jldoctest
+julia> ufac"N_A*e"
+96485.33212331001
+```
+
 """
 macro ufac_str(x)
+ esc(_ufac_str(x))
+end
+
+
+
+macro xufac_str(x)
  Unitful=getproperty(@__MODULE__,:Unitful)
  quote
  unitfactor($(Unitful),$(Unitful).@u_str($(x)))
  end
 end
 
+
+
 function _unitfactors(xs...)
  Unitful=getproperty(@__MODULE__,:Unitful)
  code = Expr(:block)
@@ -295,7 +324,6 @@ macro local_phconstants(xs...)
  esc(_local_phconstants(xs...))
 end
 
-
 export @phconstants, @local_phconstants
 
 end # module LessUnitful