Osgb

- reduced size of the data table in OSTN02 and improved loading time

- new "random_grid" function in OSGB returns a random point on a random Landranger map.
See "gbguessr.pl" script for example use to compare OS maps and Google maps on same point

- removed old kml generating example script
- revised and improved documentation

- removed dependency on Math::Trig for tan and sec functions
- removed unnecessary package variables from OSTN02
- simplified unpacking of data in OSTN02

- removed precise URL for theory paper - the OS keep moving it about, so just Google for the name
- removed non-ascii characters from POD in OSGB.pm to avoid encoding issue

- Put blank lines back in OSTN02 to prevent pod2html taking an age during install
- Refactored OSGB and OSTN02 lightly to conform more closely to "Perl Best Practices"
- corrected corner coordinate data for Landranger sheets 1 and 185

- Rework search of OSTN02 data to improve performance and reliability
- Add range checking of OSTN02 coordinates
- Compress OSTN02 data to hexadecimal form to speed up loading
- Change selection of data in 03random.t test to avoid off-the-sheet errors
- Minor tidy up changes in OSGB
- Complete overhaul of the documentation
- removed old "coco.pl" example script
- added new example script to show all "000 000" grid references