ENH: allow spaces in nested templates

[teunisv]

|table template|T I0                |
|check         |clone symbol|@{P0}|0|
|$P6=          |clone symbol|@{P1}  |

|table template|T I1                |
|check         |clone symbol|@{P3}|3|
|$P4=          |clone symbol|@{P1}  |
|T I0;                              |

|table template|T I2              |
|T I1;                            |
|$P5=          |clone symbol|@{P2}|


|script|

|T I2                   |
|P0|P1|P2|P3|P4?|P5?|P6?|
|0 |1 |2 |3 |1  |2  |1  |

For naming purpose (not checked if capitals or _ messes it up too)

[fhoeben]

The spaces are allowed in the name actually, but when called they are not handled properly.
The test does work as follows:

|table template|T I0                |
|check         |clone symbol|@{P0}|0|
|$P6=          |clone symbol|@{P1}  |

|table template|T I1                |
|check         |clone symbol|@{P3}|3|
|$P4=          |clone symbol|@{P1}  |
|TI0;                              |

|table template|T I2              |
|TI1;                            |
|$P5=          |clone symbol|@{P2}|


|script|

|T I2                   |
|P0|P1|P2|P3|P4?|P5?|P6?|
|0 |1 |2 |3 |1  |2  |1  |

I'll see whether I can fix this easily...