Add cubic volumes and oil barrels

Added cubic metres, cubic feet, cubic inches and oil barrels to volume

Added more time measurements

v0.1.18

Added millisecond, nanoseconds, microseconds to README.md

Precision fixes

v0.1.10

Updated version to match new changes

v0.1.9

Added npmignore to remove code/files/folders that are not required in the published version.

v0.1.4

Clean up of code that's not completed, added tests as well as FuelEconomy and DataTransferRate