string convertion issues, UTF-8 and memory leak issues

[jeremyVignelles]

These lines seems bogous to me:

Vlc.DotNet/src/Vlc.DotNet.Core.Interops/Extensions/IntPtrExtensions.cs

Lines 8 to 14 in 3530385

	#if !NET20
	public static string ToStringAnsi(this IntPtr ptr)
	#else
	public static string ToStringAnsi(IntPtr ptr)
	#endif
	{
	return ptr != IntPtr.Zero ? Marshal.PtrToStringAnsi(ptr) : null;

Vlc.DotNet/src/Vlc.DotNet.Core.Interops/Extensions/StringExtensions.cs

Lines 8 to 16 in 3530385

	#if !NET20
	public static IntPtr ToHGlobalAnsi(this string source)
	#else
	public static IntPtr ToHGlobalAnsi(string source)
	#endif
	{
	if (source == null)
	return IntPtr.Zero;
	return Marshal.StringToHGlobalAnsi(source);

Because:

• All string inputs in libvlc are expected as UTF-8
• IntPtr should be Free'd correctly, otherwise, memory will probably leak