Merge os, middle and meta subpackages

source/tanya/conv.d

@@ -14,11 +14,10 @@
  */
 module tanya.conv;
 
-import std.traits : Unsigned, isNumeric, Largest, Unqual, EnumMembers, isFloatingPoint, isSomeChar, isSigned,
-       isUnsigned, isIntegral, isSomeString;
+import std.traits;
 import tanya.container.string;
 import tanya.memory.allocator;
-import tanya.meta.trait;
+import tanya.meta;
 import tanya.range;
 
 /**