parametric typealias additional explanation

I added some text to clarify a point that stumped me about parametrized types and typealias.
Use a tarball instead of git for checking out LLDB.
Don't forget to download LLDB, and make python2 hack more compact.
Ignore LLDB deps, and add some checksums.
Remove unused LIBCXX_OPTIONS.
protect commit for "protect Makefile VERBOSE macros..." from unwanted ' escape
Merge pull request #9051 from maleadt/pr_lldb

Makefile clean-up (LLDB tarball, and unused variable removal)
windows: update url of mingw-w64-dgn script
Don't run appveyor on personal branches for now

they should still build when there is a PR opened for them
doc: Fix 'merge' example for 'Dict's

The output did not match inputs of the command.
Merge pull request #9172 from julian-gehring/patch-dict-merge

doc: Fix 'merge' example for 'Dict's
Document `join`'s optional `last` parameter.
Merge pull request #9159 from lucasb-eyer/join-doc

Document `join`'s optional `last` parameter.
Merge pull request #9033 from StephenVavasis/patch-13

parametric typealias additional explanation