Import initial human_readable_stmt helpers
Add Func::compile_to_simplified_lowered_stmt

Migrates most variants of human_readable_stmt.
Adds (non-verifying) test case to compile_to_lowered_stmt test.

Question: do we want to expose a simple version that returns a Stmt,
instead of always serializing to a file? How does this compose with HTML
printing?
Add, customize StmtToHtml in bilateral_grid

Still a header-only standalone test.
Move StmtToHtml into core
compile_to_lowered_stmt optionally emits HTML

Both simplified and traditional versions now emit HTML if the
filename ends in .html, traditional plain text otherwise.
addressing pull request feedback
if availible use lowered function, also start changing to default argument
renamed HumanRedableStmt::s to HumanRedableStmt::stmt
for compile_to_simplified_lowered_stmt changed get_jit_target_enviroment to get_target_enviroment
added fmt object and newlines to arguments list to make more readable
moved the StmtOutputFormat enum to make it more usable
addressed some spacing issues
fixing grammer
Bring python bindings up to date.
Merge pull request #393 from fcr/master

Bring python bindings up to date.
fixed spacing
addressing issues in comment-style and indentation
Fix typo causing memory stomping in test_memoize
modified templated compile_to_simplified_lowered_stmt
added a very basic test of stmt_to_html