HQ20 Venture ETH

Implements a venture * * 1. Use `setIssuePrice` to determine how many ether do investors * have to pay for each issued token. * 2. Use `startIssuance` to allow investors to invest. * 3. Investors can `invest` their ether at will. * 4. Investors can also `cancelInvestment` and get their ether back. * 5. The contract owner can `cancelAllInvestments` to close the investment phase. * In this case `invest` is not available, but `cancelInvestment` is. * 6. Use `startDistribution` to close the investment phase. * 7. Investors can only `claim` their issued tokens now. * 8. Owner can use `withdraw` to send collected ether to a wallet. * 9. Clients can `increasePool` of ether * 10. Investors can be returned dividends with `updateAccount`