add build script

.gitignore

@@ -1 +1,2 @@
 bin/*
+release/*

README.md

@@ -7,7 +7,7 @@ Simple GUI calculator with complex infix expression evaluation made in Java usin
 ```bash
   $ git clone --depth=1 https://github.com/krolyxon/JavaCalc --branch=master
   $ cd JavaCalc
-  $ ./run.sh
+  $ ./run.sh OR ./build.sh
   ```
 
 ## JavaCalc in action

build.sh

@@ -0,0 +1,4 @@
+#!/bin/sh
+mkdir -p release
+javac -d ./bin src/*.java
+jar cvmf manifest.mf ./release/JavaCalc.jar -C ./bin .

manifest.mf

@@ -0,0 +1 @@
+Main-Class: Calculator

run.sh

@@ -1,5 +1,6 @@
 #!/bin/sh
 mkdir -p ./bin
 ClASSNAME="Calculator"
-javac -d ./bin/ "./$ClASSNAME.java"
-java -cp ./bin/ "$ClASSNAME" $*
+cd src
+javac -d ../bin/ "./$ClASSNAME.java"
+java -cp ../bin/ "$ClASSNAME" $*