Restructure how we handle errors from build

lerna produces output that don't match well with how tsc-watch handles it. We need a different strategy. So, for now, don't use watch but explicitly build if you want to get the problem markers.

.vscode/tasks.json

@@ -33,16 +33,29 @@
             "problemMatcher": "$tsc-watch"
         },
         {
+            "isBuildCommand": true,
             "taskName": "Compile",
             "command": "lerna",
             "isShellCommand": true,
             "showOutput": "silent",
             "args": [
                 "run",
+                "--stream",
                 "compile"
             ],
             "isBackground": false,
-            "problemMatcher": "$tsc-watch"
+            "problemMatcher": {
+                "owner": "typescript",
+                "fileLocation": "relative",
+                "pattern": {
+                    "regexp": "^(@salesforce\\/)(.*)\\((\\d+)\\,(\\d+)\\):\\s+(error|warning|info)\\s+(TS\\d+)\\s*:\\s*(.*)$",
+                    "file": 2,
+                    "line": 3,
+                    "severity": 5,
+                    "code": 6,
+                    "message": 7
+                }
+            }
         }
     ]
 }

README.md

@@ -32,6 +32,10 @@ You would usually do the following each time you close/reopen VS Code:
 
 1. Open the Command Palette > Tasks: Run Task > Bootstrap  (this essentially
    runs `lerna bootstrap`).
+1. If you wish to build, you can invoke Command Palette > Build Task
+   (Ctrl+Shift+B or Cmd+Shift+B on Mac). The errors will show in the Problems
+   panel. There is a known issue with the mapping so clicking on the error won't
+   open the file.
 1. In VS Code, open the debug view (Ctrl+Shift+D or Cmd+Shift+D on Mac) and from
    the launch configuration dropdown, pick "Launch Extensions".
 1. In VS Code, open the debug view (Ctrl+Shift+D or Cmd+Shift+D on Mac) and from