piechartMP installation:

piechartmp.mp  --> TEXMF/metapost/piechartmp/
LEGAL, README  --> TEXMF/doc/metapost/piechartmp/
piechartmp.pdf --> TEXMF/doc/metapost/piechartmp/
/examples/*    --> TEXMF/doc/metapost/piechartmp/
