Freetype: split some functions in text_renderer.c

Too many functions are not related to freetype and could be used by
other renderers like QuartText or DirectWrite.
Moreover, this file was way too long.

This is just the beginning, and there are no functionnal change so far.

modules/text_renderer/Modules.am

-SOURCES_freetype = freetype.c
+SOURCES_freetype = freetype.c text_renderer.c text_renderer.h
 SOURCES_quartztext = quartztext.c
 SOURCES_svg = svg.c
 SOURCES_tdummy = tdummy.c

modules/text_renderer/text_renderer.h

+/*****************************************************************************
+ * text_renderer.h : fonts, text styles helpers
+ *****************************************************************************
+ * Copyright (C) 2002 - 2013 VLC authors and VideoLAN
+ * $Id$
+ *
+ * Authors: Sigmund Augdal Helberg <dnumgis@videolan.org>
+ *          Gildas Bazin <gbazin@videolan.org>
+ *          Bernie Purcell <bitmap@videolan.org>
+ *          Jean-Baptiste Kempf <jb@videolan.org>
+ *          Felix Paul Kühne <fkuehne@videolan.org>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation, Inc.,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#include <vlc_text_style.h>                                   /* text_style_t*/
+
+/* fonts and font_stack_t functions */
+typedef struct font_stack_t font_stack_t;
+struct font_stack_t
+{
+    char          *psz_name;
+    int            i_size;
+    uint32_t       i_color;            /* ARGB */
+    uint32_t       i_karaoke_bg_color; /* ARGB */
+
+    font_stack_t  *p_next;
+};
+
+int PushFont( font_stack_t **p_font, const char *psz_name, int i_size,
+              uint32_t i_color, uint32_t i_karaoke_bg_color );
+
+int PopFont( font_stack_t **p_font );
+
+int PeekFont( font_stack_t **p_font, char **psz_name, int *i_size,
+              uint32_t *i_color, uint32_t *i_karaoke_bg_color );
+
+int HandleFontAttributes( xml_reader_t *p_xml_reader,
+                          font_stack_t **p_fonts );
+
+int HandleTT(font_stack_t **p_fonts, const char *p_fontfamily );
+
+/* Turn any multiple-whitespaces into single spaces */
+void HandleWhiteSpace( char *psz_node );
+
+/* text_style_t functions */
+text_style_t *CreateStyle( char *psz_fontname, int i_font_size,
+                           uint32_t i_font_color, uint32_t i_karaoke_bg_color,
+                           int i_style_flags );
+
+#ifdef __OS2__
+typedef uint16_t uni_char_t;
+# define FREETYPE_TO_UCS    "UCS-2LE"
+#else
+typedef uint32_t uni_char_t;
+# if defined(WORDS_BIGENDIAN)
+#  define FREETYPE_TO_UCS   "UCS-4BE"
+# else
+#  define FREETYPE_TO_UCS   "UCS-4LE"
+# endif
+#endif
+
+unsigned SetupText( filter_t *p_filter,
+                    uni_char_t *psz_text_out,
+                    text_style_t **pp_styles,
+                    uint32_t *pi_k_dates,
+                    const char *psz_text_in,
+                    text_style_t *p_style,
+                    uint32_t i_k_date );
+
+bool FaceStyleEquals( const text_style_t *p_style1,
+                      const text_style_t *p_style2 );
+