General engine improvements (#437)

* Add exchange manager to engine

* Several improvements for engine and friends

1) New file.Exists func
2) gRPC TLS cert expiration date check and regeneration
3) New donation var for use across the codebase
4) Use Go log package until the logger is initialised

* Add cert tests and create dir tree if it doesn't exist for file.Write

* Link up donation address to documentation tool plus minor adjustments

* Fix remaining donation addrs

* Move non-needed reload exchange funcs

* Revert accidental config_example.json changes 🕯️

* Use go logger for logging until the logger has initiliased, otherwise no output will be seen

* Link up portfolio delay val and other fixes

* Run go mod tidy after dependabot PR

* Address nitterinos

cmd/documentation/root_templates/root_readme.tmpl

@@ -59,7 +59,7 @@ We are aiming to support the top 20 highest volume exchanges based off the [Coin
 + REST API support for all exchanges.
 + Websocket support for applicable exchanges.
 + Ability to turn off/on certain exchanges.
-+ Communication packages (Slack, SMS via SMSGlobal, Telegram and SMTP)
++ Communication packages (Slack, SMS via SMSGlobal, Telegram and SMTP).
 + HTTP rate limiter package.
 + Unified API for exchange usage.
 + Customisation of HTTP client features including setting a proxy, user agent and adjusting transport settings.
@@ -69,10 +69,11 @@ We are aiming to support the top 20 highest volume exchanges based off the [Coin
 + Connection monitor package.
 + gRPC service and JSON RPC proxy. See [gRPC service](/gctrpc/README.md).
 + gRPC client. See [gctcli](/cmd/gctcli/README.md).
-+ Forex currency converter packages (CurrencyConverterAPI, CurrencyLayer, Fixer.io, OpenExchangeRates)
++ Forex currency converter packages (CurrencyConverterAPI, CurrencyLayer, Fixer.io, OpenExchangeRates).
 + Packages for handling currency pairs, tickers and orderbooks.
 + Portfolio management tool; fetches balances from supported exchanges and allows for custom address tracking.
 + Basic event trigger system.
++ Scripting support. See [gctscript](/gctscript/README.md).
 + WebGUI (discontinued).
 
 ## Planned Features
@@ -120,13 +121,7 @@ copy config_example.json %APPDATA%\GoCryptoTrader\config.json
 + Make any neccessary changes to the `config.json` file.
 + Run the `gocryptotrader` binary file inside your GOPATH bin folder.
 
-## Donations
-
-<img src="https://github.com/thrasher-corp/gocryptotrader/blob/master/web/src/assets/donate.png?raw=true" hspace="70">
-
-If this framework helped you in any way, or you would like to support the developers working on it, please donate Bitcoin to:
-
-***1F5zVDgNjorJ51oGebSvNCrSAHpwGkUdDB***
+{{template "donations" .}}
 
 ## Binaries