1.4.6

#39 Switch to "github.com/edsrzf/mmap-go" for cross-platform mmap implementation (to make Windows builds work again)
#37 import: JSON input processing supports --fields and --fields-from-header flags
#30 added type sizes info found within the data section)
#28 added low-level mmdb data to the metadata output
#26 Fix: Compatibility Issue with IP2Location DB using int for IP Range

1.4.4