rename some of the classes

CParser is now just parser. CTree is now Schema. The namespace "schema" is
now called "yang".

Change-Id: Ief9c22fb6a7633b80010d355f9582e313e818d45
diff --git a/src/parser_context.cpp b/src/parser_context.cpp
index db2bb43..d3b4a90 100644
--- a/src/parser_context.cpp
+++ b/src/parser_context.cpp
@@ -7,8 +7,8 @@
 */
 
 #include "parser_context.hpp"
-ParserContext::ParserContext(const CTree& tree, const path_ curDir)
-        : m_tree(tree)
+ParserContext::ParserContext(const Schema& schema, const path_ curDir)
+    : m_schema(schema)
 {
     m_curPath = curDir;
 }