Adds random number generation for BigInts from GMP
Refactor BigInt RNG
Add a default BigRNG and the standard interface to seed BigRNGs
Add BigFloat random number generation
Improved support for random BigInt ranges

This means that ranges between numbers bigger than `typemax(Int)` work
now, but range lengths are still limited to up to `typemax(Int)`.
Add normally-distributed BigFloats generation
srand() now seeds both RNGs
Use `shasum` instead of `sha1sum` in OS X

OS X doesn't have `sha1sum` available, so the fallback used to get
the initial seed whenever /dev/urandom isn't available doesn't work.
Add documentation to the BigRNG
generalize writedlm to iterable arguments and arbitrary delimeters
Update Makefile

1. Preserve the timestamp by replacing cp with install -p
2. Restrict file permissions by install -m
mkdir -p $(DESTDIR)$(SYSCONFDIR)

mkdir -p $(DESTDIR)$(SYSCONFDIR)
Update $(DESTDIR)$(PREFIX) in comments

--- we always install to PREFIX/etc.
+++ we always install to $(DESTDIR)$(PREFIX)/etc.
Translate Givens rotations from LAPACK to Julia.
expm: fixed rescaling
Add Givens and Rotation types.
support multiple/matrix right-hand sides in sparse A \ B
adds section on passing pointers to C functions for modification
Use debug executable on Travis
fix #5210, factor() failing for some integer types