Remove language_uit as it is no longer used

Use initialize_goto_model to obtain goto programs, don't run parse() etc.
directly.

Author: tautschnig

doc/architectural/code-walkthrough.md

@@ -14,7 +14,7 @@ See \ref goto-programs, \ref goto_programt and [instructiont](\ref goto_programt
 
 \section front-end-languages-generating-codet-from-multiple-languages-section Front-end languages: generating codet from multiple languages
 
-\subsection language-uit-section language_uit, language_filest, languaget classes:
+\subsection language-uit-section language_filest, languaget classes:
 
 See \ref langapi.
 

src/langapi/Makefile

@@ -1,5 +1,4 @@
-SRC = language_ui.cpp \
-      language_util.cpp \
+SRC = language_util.cpp \
       language_file.cpp \
       language.cpp \
       mode.cpp \

src/langapi/README.md

@@ -19,10 +19,6 @@ To be documented.
 
 To be documented.
 
-\section langapi-manipulation-framework The top-level language-file manipulation framework (language_uit, obsolete, replaced by initialize_goto_model)
-
-To be documented.
-
 \section langapi-mode-related-utils Symbol mode-related utilities (everything in mode.h)
 
 To be documented.