continued refactoring, fixing small issues in code analysis, some small features added
-added changelog.html (to mantain the full changelog)

activity_main.xml, MainActivity.java:
-added basic textview to indicate that there are no calendar entries, code swaps between the listview and the textview as needed
-different color for cancel quicksilence button

donate-key:
-reset target, min, and compile API versions to 14

-added Dialog theme to styles.xml for base theme and API 21 theme