Improving precision of number to zt-string conversion, adding search for the shortest representation of number during the conversion.

tests/unit/test_string_to_number.c

@@ -51,12 +51,12 @@ main( int __unused argc,
 
   const ecma_number_t nums[] =
   {
-    1.0f,
-    0.5f,
-    12345.0f,
-    1.0e-45f,
-    -2.5e+38f,
-    -2.5e+38f,
+    1.0,
+    0.5,
+    12345.0,
+    1.0e-45,
+    -2.5e+38,
+    -2.5e+38,
     NAN,
     NAN,
     NAN,
@@ -67,8 +67,8 @@ main( int __unused argc,
     NAN,
     INFINITY,
     -INFINITY,
-    +0.0f,
-    -0.0f
+    +0.0,
+    -0.0
   };
 
   for (uint32_t i = 0;