Eliminate all unnecessary uses of L and _T

aegisub/src/aegisublocale.cpp

aegisub/src/ass_attachment.cpp

aegisub/src/ass_dialogue.cpp

aegisub/src/ass_entry.cpp

aegisub/src/ass_file.cpp

aegisub/src/ass_file.h

aegisub/src/ass_override.cpp

aegisub/src/ass_style.cpp

aegisub/src/ass_style_storage.cpp

aegisub/src/ass_time.cpp

aegisub/src/audio_controller.cpp

aegisub/src/audio_display.cpp

aegisub/src/audio_player.cpp

aegisub/src/audio_player_dsound.cpp

aegisub/src/audio_player_dsound2.cpp

aegisub/src/audio_player_openal.cpp

aegisub/src/audio_player_oss.cpp

aegisub/src/audio_player_portaudio.cpp

aegisub/src/audio_player_pulse.cpp

aegisub/src/audio_provider_avs.cpp