Early buffer implementation for the Java codegen
modify RTS so that it can be built single-threaded if pthreads are not available.
fixups for HAS_PTHREAD changes
hack in idris_gc to force 16-bit/2-byte alignment for
allocations. Some embedded platforms, like the arduino/avr, support
byte-aligned pointers. However, that makes implementing tagged
pointers very tricky. So, instead we just force 16-bit alignment.
remove #include <unistd.h>. Not all platforms provide that header, and it does not seem to be required anyway.
force tag_arity and ty to be uint32_t instead of system dependent int sizes.
Changed some ints to size_t. Seems valid -- not certain.
should have been in the last commit.
Change + to | because | better reflects our intentions.
alloc_heap also requires the pointer alignment hack.
Minor fixes for the Java backend
Merge branch 'master' into JavaBackendFixes
* Make regression test029 work by adding a wrapper loading environment variables to properties
* Include sugar004
added "prim__registerPtr" noop for Java
Merge branch 'JavaBuffers' into JavaBackendFixes

Conflicts:
	src/IRTS/CodegenJava.hs
Add superclass info to ClassDoc and output it in pprintDocs (:doc command)
Split :apropos queries at spaces, treat as conjunction

This makes it easier to narrow queries
:apropos syntax for binders

Together with space splitting, this lets :apropos be used as a kind of
dumber Hoogle. For instance:

```
Idris> :apropos nat -> string
Prelude.Strings.length : String -> Nat
Returns the length of the string.

Idris> :apropos fin -> string

Idris> :apropos fin -> plus

Idris> :apropos fin -> +
Prelude.Fin.+ : Fin n -> Fin m -> Fin (n + m)
Add two Fins, extending the bound

Prelude.Fin.shift : (m : Nat) -> Fin n -> Fin (m + n)
Add some natural number to a Fin, extending the bound accordingly

Prelude.Fin.weakenN : (n : Nat) -> Fin m -> Fin (m + n)
Weaken the bound on a Fin by some amount
```
Document :apropos updates in CHANGELOG
Merge pull request #1189 from david-christiansen/apropos-improvements

Apropos improvements