Fixed file_istream's seekg() and added writeat() to mem_ostream and m…

…emfile_ostream

Remove <iostream> header

Add overloaded open functions that take in wchar file parameter

Use is_arithmetic instead of is_integral to determine swapping

Update version

Fix ptr_istream reading empty string

Fix GCC and Clang Template errors

Update README

Using C File APIs, instead of STL file streams

Update README.md for Version 0.9.5