fixed compilation errors when using amalgamation in visual studio, maintained gcc and mingw builds. ln103: do not step on math.h functions on *nix systems and cygwin, ln117: supply isnan for visual studio builds, ln138: when using sqlite's tcl parser this created nested comments causing a syntax error.
fixed compilation errors when using amalgamation in visual studio, maintained gcc and mingw builds. ln103: do not step on math.h functions on *nix systems and cygwin, ln117: supply isnan for visual studio builds, ln138: when using sqlite's tcl parser this created nested comments causing a syntax error.

boundlessgeo/sqlite-jdbc,boundlessgeo/sqlite-jdbc,boundlessgeo/sqlite-jdbc