Replace raw UTF8 parser with String parser (#6)

* Replace UTF8 parser with String based one

* swift format

* Add parsing errors that include context about where error is

* Remove old error tests

Tests/HummingbirdMustacheTests/ErrorTests.swift

@@ -0,0 +1,79 @@
+import HummingbirdMustache
+import XCTest
+
+final class ErrorTests: XCTestCase {
+    func testSectionCloseNameIncorrect() {
+        XCTAssertThrowsError(try HBMustacheTemplate(string: """
+        {{#test}}
+        {{.}}
+        {{/test2}}
+        """)) { error in
+            switch error {
+            case let error as HBMustacheTemplate.ParserError:
+                XCTAssertEqual(error.error as? HBMustacheTemplate.Error, .sectionCloseNameIncorrect)
+                XCTAssertEqual(error.context.line, "{{/test2}}")
+                XCTAssertEqual(error.context.lineNumber, 3)
+                XCTAssertEqual(error.context.columnNumber, 4)
+
+            default:
+                XCTFail("\(error)")
+            }
+        }
+    }
+
+    func testUnfinishedName() {
+        XCTAssertThrowsError(try HBMustacheTemplate(string: """
+        {{#test}}
+        {{name}
+        {{/test2}}
+        """)) { error in
+            switch error {
+            case let error as HBMustacheTemplate.ParserError:
+                XCTAssertEqual(error.error as? HBMustacheTemplate.Error, .unfinishedName)
+                XCTAssertEqual(error.context.line, "{{name}")
+                XCTAssertEqual(error.context.lineNumber, 2)
+                XCTAssertEqual(error.context.columnNumber, 7)
+
+            default:
+                XCTFail("\(error)")
+            }
+        }
+    }
+
+    func testExpectedSectionEnd() {
+        XCTAssertThrowsError(try HBMustacheTemplate(string: """
+        {{#test}}
+        {{.}}
+        """)) { error in
+            switch error {
+            case let error as HBMustacheTemplate.ParserError:
+                XCTAssertEqual(error.error as? HBMustacheTemplate.Error, .expectedSectionEnd)
+                XCTAssertEqual(error.context.line, "{{.}}")
+                XCTAssertEqual(error.context.lineNumber, 2)
+                XCTAssertEqual(error.context.columnNumber, 6)
+
+            default:
+                XCTFail("\(error)")
+            }
+        }
+    }
+
+    func testInvalidSetDelimiter() {
+        XCTAssertThrowsError(try HBMustacheTemplate(string: """
+        {{=<% %>=}}
+        <%.%>
+        <%={{}}=%>
+        """)) { error in
+            switch error {
+            case let error as HBMustacheTemplate.ParserError:
+                XCTAssertEqual(error.error as? HBMustacheTemplate.Error, .invalidSetDelimiter)
+                XCTAssertEqual(error.context.line, "<%={{}}=%>")
+                XCTAssertEqual(error.context.lineNumber, 3)
+                XCTAssertEqual(error.context.columnNumber, 4)
+
+            default:
+                XCTFail("\(error)")
+            }
+        }
+    }
+}