1. Spheroids comprising one or more active principles, with the exception of tiagabine, wherein said spheroids further comprise: a core and a layer coating said core, wherein said layer comprises at least one thermoplastic excipient which is of pasty to semi-solid consistency at a temperature of about 20 degree C. and whose melting point is between about 25 degree C. and about 100 degree C., coated with a flexible and deformable film, based on a polymer material, with a glass transition temperature being preferably less than 30 degree C., which ensures either protection or masking of the taste, or modified and controlled release of said one or more active principles, wherein said spheroids can be compressed adding up to 5% by weight of an auxiliary substance. 2. Spheroids according to claim 1, wherein said thermoplastic excipient is chosen from partially hydrogenated oils, beeswax, carnauba wax, paraffin waxes, silicone waxes, C12-C18 fatty alcohols and fatty acids, solid, semi-synthetic glycerides, glycerol monoesters, diesters or triesters, polyoxy-ethylene glycols and glycosylated polyoxyethylenated glycerides, and mixtures thereof. 3. Spheroids according to claim 1 or 2, wherein said glass transition temperature of said flexible and deformable film is less than about 20 degree C. 4. Spheroids according to any one of claims 1 to 3, wherein said polymer material is a polymer or a mixture of at least one polymer and a plasticizer. 5. Spheroids according to claim 4, wherein said plasticizer is chosen from triethyl citrate, acetyl triethyl citrate, tributyl citrate, acetyl tributyl citrate, triacetin, diethyl phthalate, polyethylene glycols, polysorbates, mono- and diacetylated glycerides, and mixtures thereof. 6. Spheroids according to any one of claims 1 to 5, wherein said polymer material has a percentage of elongation of greater than about 50%. 7. Spheroids according to any one of claims 1 to 6, wherein said spheroids are coated with a water-dispersible outer layer which provides said spheroids with cohesion during a compression step and which ensures breakdown in aqueous medium of the tablet obtained. 8. Spheroids according to claim 7, wherein said water-dispersible outer layer consists of an acrylic, vinyl or cellulose polymer. 9. Spheroids according to any one of claims 1 to 8, wherein said one or more active principles are dispersed in the bulk of said core. 10. Spheroids according to any one of claims 1 to 8, wherein said one or more active principles are dispersed in said layer containing at least one thermoplastic excipient. 11. Spheroids according to any one of claims 1 to 8, wherein said one or more active principles are dispersed in the bulk of said core and in said layer containing at least one thermoplastic excipient. 12. Spheroids according to any one of claims 1 to 8, wherein said one or more active principles are applied to the surface of said core and then coated with said layer containing at least one thermoplastic excipient. 13. A process for the preparation of the spheroids according to any one of claims 1 to 12, wherein said layer containing at least one thermoplastic excipient and said film containing a polymer material are successively deposited on the cores by spraying, in a granulating turbomixer, in a perforated turbomixer, or in a fluidized-air bed or by any other suitable process. 14. Multiparticulate pharmaceutical preparations comprising said spheroids according to any one of claims 1 to 12 and prepared according to the process of claim 13. 15. The pharmaceutical preparations according to claim 14, wherein said pharmaceutical preparations are in the form of gelatin capsules filled with said spheroids. 16. The pharmaceutical preparations according to claim 14, wherein said pharmaceutical preparations are in the form of tablets comprising said spheroids. 17. The pharmaceutical preparations according to claim 16, wherein said tablets comprising said spheroids are prepared by a compression and addining up to 5% by weight of auxiliary substance. 18. The process according to claim 17, wherein up to 5% by weight of talc is added to said spheroids before said compression step.