Organize Makefile.am

Set headers parser.cpp includes to libparser_a_SOURCES.
Fix: add missing member

Add type_name_ member to following classes.
* MutableVariableDefinitionData
* ImmutableVariableDefinitionData
Add parse_variable_definition_statement() member

Add also parse_variable_definition() member declaration.
Add parse_variable_definition() member
Add parse_if_statement() member