* Now all traffic is going over Tor (price requests from Poloniex could not be routed over Tor because they use Cloudflare)
* Added request to CoinMarketCap to get more prices for altcoins not listed at Poloniex
* Use 2 proxy price feed providers as hidden service for requesting accumulated BitcoinAverage (new API), Poloniex and CoinMarketCap price data
* Add program argument to add custom price feed providers
* Add module for running a own proxy price feed provider (requires BitcoinAverage API keys). Supports both clearnet and hidden service
* Display time of latest price update at tooltip over provider icon in market price widget
* Remove http proxy option because it is not needed anymore (Cloudflare issue with Poloniex solved by the proxy)
* Remove tor bridge support (was not solving GFW issues and caused only problems when connections to Tor failed at startup)
