add textviewer plugin

apps/files_textviewer/appinfo/app.php

apps/files_textviewer/appinfo/info.xml

apps/files_textviewer/css/style.css

apps/files_textviewer/css/syntaxhighlighter/shCore.css

.../files_textviewer/css/syntaxhighlighter/shCoreDefault.css

apps/files_textviewer/css/syntaxhighlighter/shCoreDjango.css

.../files_textviewer/css/syntaxhighlighter/shCoreEclipse.css

apps/files_textviewer/css/syntaxhighlighter/shCoreEmacs.css

...les_textviewer/css/syntaxhighlighter/shCoreFadeToGrey.css

.../files_textviewer/css/syntaxhighlighter/shCoreMDUltra.css

...files_textviewer/css/syntaxhighlighter/shCoreMidnight.css

apps/files_textviewer/css/syntaxhighlighter/shCoreRDark.css

...files_textviewer/css/syntaxhighlighter/shThemeDefault.css

.../files_textviewer/css/syntaxhighlighter/shThemeDjango.css

...files_textviewer/css/syntaxhighlighter/shThemeEclipse.css

apps/files_textviewer/css/syntaxhighlighter/shThemeEmacs.css

...es_textviewer/css/syntaxhighlighter/shThemeFadeToGrey.css

...files_textviewer/css/syntaxhighlighter/shThemeMDUltra.css

...iles_textviewer/css/syntaxhighlighter/shThemeMidnight.css

apps/files_textviewer/css/syntaxhighlighter/shThemeRDark.css