Merge pull request #36 from dmb2168/master

Updating Chris/Kira with Master
added root function with tests
switching int16_t to int to get rid of compiler warnings of pointer assignment
Merge branch 'chris_kira_semantic_analysis' of https://github.com/dmb2168/PLT into chris_kira_semantic_analysis
trees of degree 0 (t = 6[]) can be used in assignment
Merge pull request #38 from dmb2168/master

Added Mod. Zharn added Fail Test
null literal working; can compare trees with null :)
Merge branch 'chris_kira_semantic_analysis' of https://github.com/dmb2168/PLT into chris_kira_semantic_analysis
null/tree comp neq and eq
fixed function call with trees
Merge pull request #37 from dmb2168/chris_kira_semantic_analysis

Depth First Search Working