Made project file and Calculator package header

Calculator has only one procedure for now: start Calculator.
Made the ExpressionTree package and body

I implemented most of the package. I know I should have commited more.
Right now, the evaluation function isn't implemented and the header of
ExpressionTree won't compile for some reason
Changed Integer to Long_Float and bug fixes

Changed Integer in the operator functions to Long_Float so that decimal
numbers can be used. Had to bring in
Ada.Numerics.Generic_Elementary_Functions so that we had a power
function. Also fixed some bugs, namely function definitions not matching
specification and evaluateTree(extree.right) to return
evaluateTree(extree.root.right)
added expression printing functions

added printTreeInFix and printTreePreFix
implemented evaluateTree

evaluateTree is implemented but I have to change isOperator to accept a
String instead of an unbounded string
changed argument of isOperator

changed isOperator from accepting unbounded strings to String and
changed calls to isOperator to reflect the new argument
added helper functions for printing functions

I also changed the documentation for evaluateTree's helper function to
better reflect its function
Corrected arguments of printing functions
Implemented printTreeInFix
Implemented printTreePreFix
changed addFinalNumber

changed addFinalNumber so that it doesn't do anything if the expression
tree's current number is null. It also sets the current number of the
expression to null when it gets done adding it to the tree.
added a procedure to test ExpressionTree
changed expressiontreetester + made it main file

changed the test expression into an array of unbounded strings. The
initialization statement is uglier now, but it will now at least compile
fixed bugs

The calculator now works! however, it outputs answers in E notation. I
plan to make a function that will convert it to a more standard format
added convertFromE

added the convertFromE function in the source code
fixed faulty convertFromE declaration
fixed Float output format in expressiontreetester

Removed convertFromE since I didn't need it. You could use
expressiontreetester to see how to change it from E notation
Merge pull request #1 from jacobmedd/Jacob-Branch

Jacob branch