newNode, deleteNode > appendNode, removeNode / gpdsp bug fixes / impr…

…ove doxygen document

GPDSPPeekNode > GPDSPPeakNode / added doxygen document

Update README.md

Update README.md

added SignNode, SquareRootNode / supports 32bits and 64bits floating …

…points

supports negative inputs and constant inputs

added synthesis components / improve algorithm

improve algorithm / supports generic filters

updated