Refactor Expr Parser.
Further parser refactoring.
Adding more default functions.
Minor Cabal/Haddock fixes.
Guard against spikes in mesh generation.
Fix the overlapping Show (a -> b) instance bug.
Fix (<>) ambiguity in extopenscad.hs.
Actually fix compatibility for options.applicative.
Merge remote-tracking branch 'remotes/origin/parser-refactor' into pre-optparse
Merge branch 'pre-optparse'
Parser fix, missing trys.

Apparently sepBy breaks when the separator fails after consuming some
input. A few trys solve this issue, at the cost of mildly less pleasent
code.
Add rotation while rotate_extruding.
Use the Show instance from Data.NumInstances for functions
rather than defining one locally.

The local definition conflicts in some cases, and prevents compiling.
exprN takes Integer, not Int
Add type signature for expr0.

Both changes are necessary to compile.
Merge pull request #96 from bergey/build-fix

Build fix
Switch (&) to (<>) to avoid deprication warning.
Set version to 0.0.3 (most recent release).

0.0.3 was actualy created on a different branch, but we shouldn't have
development be a lower version...
Fix a few typos