Split path_ into schemaPath_ and dataPath_

This change is necessary because different commands accept different
kinds of paths (for example "cd" only accepts a data path, on the other
hand "ls" doesn't care about data, so it accepts both). One option was to
create a new path struct for every command, but that could get quickly
out of control as new commands get added. The other option was define only
the data path and schema path and then change the commands' grammars, so
that they only accept the relevant paths, but in the end always return a
data path or a schema path.

Change-Id: I7668a446fbf674c7a5deae22d9aacdfb3da9b07e
diff --git a/src/parser_context.cpp b/src/parser_context.cpp
index fa64344..f5e2d32 100644
--- a/src/parser_context.cpp
+++ b/src/parser_context.cpp
@@ -7,7 +7,7 @@
 */
 
 #include "parser_context.hpp"
-ParserContext::ParserContext(const Schema& schema, const path_ curDir)
+ParserContext::ParserContext(const Schema& schema, const schemaPath_& curDir)
     : m_schema(schema)
 {
     m_curPath = curDir;