update target sdk and performance improvement

bugfix for the amortization worksheet.

Cash flow worksheet optimization.

Add more functions in Cash Flows worksheet.

UI optimization

bugfix for iOS 13.

bug fix on margin calculation.

bug fix.

bug fix.

1. add Tip Calculator feature.
2. minor bug fixes.

now on Apple Watch

fixed the Cash Flow bug.

- upgrade to iOS 8.
- be sure to check out our 10bii & 12C Financial Calculator bundle, and get the popular 12C Financial Calculator at only 1$ more.

minor bug fixes.

minor bug fixes.

minor bug fix.

fix the calculation bug in EU number format.

minor bug fixes.

1. add TVM spreadsheet like worksheet to ease TVM calculation.
2. bug fixes.