Rework ToSql to be implementable without unsafe.

src/functions.rs

@@ -182,7 +182,7 @@ impl<'a> ValueRef<'a> {
 
                 ValueRef::Blob(from_raw_parts(blob as *const u8, len as usize))
             }
-            _ => unreachable!("sqlite3_value_type returned invalid value")
+            _ => unreachable!("sqlite3_value_type returned invalid value"),
         }
     }
 }
@@ -219,7 +219,7 @@ impl<'a> Context<'a> {
         let value = unsafe { ValueRef::from_value(arg) };
         FromSql::column_result(value).map_err(|err| match err {
             Error::InvalidColumnType => Error::InvalidFunctionParameterType,
-            _ => err
+            _ => err,
         })
     }