(Exchanges) Introduce validation method and small updates (#565)

* Remove pointer reference

* Fix portfolio withdraw tests

* Add nil protection in validator method to reduce prospective panics and for future outbound checking

* Updated tests

* ch order var to not ref package

* rm comparison

* Add order ID validation check

* Add exchange name validation check

* Add in test details

* fix tests

* fix linter issues

* linter issues strikes again

* linter rabbit hole

* Addr nitterinos

* Add validation variadic interface to define sets of functionality check POC

* didn't want to add an amount other than 0, didn't want to add address to exchange withdraw, didn't want to whitlist, can change if need be

* add coverage

* Add validation method options for exchange wrappers and abstracted validation into its own package

* Add validation code for structs in exchange template generation

* remove extra validation call as this is done in wrapper

* fix niterinos for examplerinos

* Add template to documentation tool and regenerated documentation

* Addr niticles

* Fix tests due to validation update

* Add more validation checks for modify/submit orders

* update tests

* fix more tests

* Add asset type to submit variable in tests and rpc call. Regen funcs.

* Add field to modify struct in tests

* applied field asset to cancel struct across project

* fix woopsy

cmd/documentation/documentation.go

@@ -169,8 +169,11 @@ func main() {
 
 		// Github API missing contributors
 		contributors = append(contributors, []Contributor{
-			// idoall's contributors were forked and merged, so his contributions
-			// aren't automatically retrievable
+			{
+				Login:         "daniel-cohen",
+				URL:           "https://github.com/daniel-cohen",
+				Contributions: 1,
+			},
 			{
 				Login:         "DirectX",
 				URL:           "https://github.com/DirectX",
@@ -181,6 +184,8 @@ func main() {
 				URL:           "https://github.com/frankzougc",
 				Contributions: 1,
 			},
+			// idoall's contributors were forked and merged, so his contributions
+			// aren't automatically retrievable
 			{
 				Login:         "idoall",
 				URL:           "https://github.com/idoall",