make gdal lib check more robust
scons: fix configure check for sqlite_rtree on linux when sqlite3 is statically linked
scons: when linking statically on linux always link -ldl
MinGW support for SConstruct script. Build now properly detects MinGW and finds dependencies correctly.
format update
Properly Initialize mingwbuild variable.
Added singleton unit test to check for multiple instances across multiple dynamic libraries.
Updates for supporting 64bit MinGW build on Windows 7+ via GNU tools.
Final MinGW 64 bit enhancements for Windows 7+ and Server 2008+