add code & testing files for continue-on-error flag

- add continue-on-error flag as a command line option
    - if set, doesnt exit on error and continues
        processing other files that were passed in
- add fatalErrorHandler to handle fatal errors
    - if continue-on-error flag is set, does not exit
- add temporary tests for continue-on-error flag
    - add tests in batch-tests subdirectory

testdata/batch-tests/broken-test.md

@@ -0,0 +1,15 @@
+# a
+
+## b
+
+### c
+
+#### d
+
+##### e
+
+# f
+
+## g
+
+# This/is some_Heading.yml

testdata/batch-tests/irfan-test.md

@@ -0,0 +1,10 @@
+<!-- Space: MySpace -->
+<!-- Parent: Parent -->
+<!-- Title: whatnot -->
+
+## Foo
+
+> **TL;DR:** Thingy!
+> More stuff
+
+Foo

testdata/batch-tests/mark-test.md

@@ -0,0 +1,15 @@
+# a
+
+## b
+
+### c
+
+#### d
+
+##### e
+
+# f
+
+## g
+
+# This/is some_Heading.yml

testdata/batch-tests/rich-test.md

@@ -0,0 +1,19 @@
+<!-- Space: TEST2 -->
+<!-- Title: H2 -->
+<!-- Title: whatnot -->
+
+# a
+
+## b
+
+### c
+
+#### d
+
+##### e
+
+# f
+
+## g
+
+# This/is some_Heading.yml