toLower

[Joel]

How come toLower works in the sort quotes, but not in the map?

```d
void main() {
     import std;
     "EzraTezla"
         .to!(char[])
         .byCodeUnit
         .sort!"a.toLower<b.toLower"
         .map!(c => c.toLower)
         .writeln;
}
```

onlineapp.d(60): Error: `toLower` matches conflicting symbols:
/dlang/dmd/linux/bin64/../../src/phobos/std/uni/package.d(9819):  
       function `std.uni.toLower`
/dlang/dmd/linux/bin64/../../src/phobos/std/ascii.d(637):        
function `std.ascii.toLower!char.toLower`
/dlang/dmd/linux/bin64/../../src/phobos/std/algorithm/iteration.d(479):        instantiated from here: `MapResult!(__lambda4, SortedRange!(ByCodeUnitImpl, "a.toLower>b.toLower", SortedRangeOptions.assumeSorted))`
onlineapp.d(60):        instantiated from here: 
`map!(SortedRange!(ByCodeUnitImpl, "a.toLower>b.toLower", 
SortedRangeOptions.assumeSorted))`