= To expose PrecisionModel through C-API =

 * Create a function GEOSPrecisionModel in geos_c.cpp which calls GEOSPrecisionModel_r in geos_ts_c.cpp to make it thread safe.
 * GEOSPrecisionModel_r creates a new precision model with arguments (double newScale, double newOffsetX, double newOffsetY) with fixed precision(the arguments that need to be passed are to be finalized).
 * Create a new geometry factory by passing this precision model to it.
 * Create a function GEOSContext_setPrecisionModel which sets the geometry factory and precision model to be used in that context.
 * Write test cases.