add basic request caching with sqlite
remove access token from URL
also store other response codes in the cache
compress data and store type
parse cache-control and last-modified headers
don't report SQLITE_OK as an error
add missing headers
link dependencies with sqlite3
fix issue that deleted the data part of a std::string as a std::string object
add libcurl build
fix build issues
pass libuv, libcurl and boost headers down to dependents
add -g
remove shared_from_this() usage
do 304 requests and cache them in sqlite
make sure all of our async handles are stopped before stopping the map thread
use util::ptr as a wrapper around std::shared_ptr that asserts nonemptiness
use separate workers for tile parsing to avoid blocking the threadpool for other libuv actions
notifications on request cancellation
add a callback to stop() to allow running the current thread's event loop