This fixes 3 warnings from compiling the DILParser:
DILParser.h:53:12: warning: returning address of local temporary object
[-Wreturn-stack-address]
DILParser.h:119:8: warning: private field 'm_fragile_ivar' is not used
[-Wunused-private-field]
DILParser.h:120:8: warning: private field 'm_check_ptr_vs_member' is not
used [-Wunused-private-field]
Add the Data Inspection Language (DIL) implementation pieces for
handling plain local and global variable names.
See https://discourse.llvm.org/t/rfc-data-inspection-language/69893 for
information about DIL.
This change includes the basic AST, Lexer, Parser and Evaluator pieces,
as well as some tests.
